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2012 TECHNICAL REPORT Assessment and Mapping of the Riverine Hydrokinetic Resource in the Continental United States

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Page 1: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

2012 TECHNICAL REPORT

Assessment and Mapping of the Riverine Hydrokinetic Resource in the Continental United States

EPRI Project Manager P Jacobson

3420 Hillview Avenue Palo Alto CA 94304-1338

USA

PO Box 10412 Palo Alto CA 94303-0813

USA

8003133774 6508552121

askepriepricom

wwwepricom

Assessment and Mapping of the Riverine Hydrokinetic

Energy Resource in the Continental United States

1026880 Final Report December 2012

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES

THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE INC (EPRI) NEITHER EPRI ANY MEMBER OF EPRI ANY COSPONSOR THE ORGANIZATION(S) BELOW NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM

(A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER EXPRESS OR IMPLIED (I) WITH RESPECT TO THE USE OF ANY INFORMATION APPARATUS METHOD PROCESS OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS INCLUDING ANY PARTYS INTELLECTUAL PROPERTY OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USERS CIRCUMSTANCE OR

(B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION APPARATUS METHOD PROCESS OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT

REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT PROCESS OR SERVICE BY ITS TRADE NAME TRADEMARK MANUFACTURER OR OTHERWISE DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT RECOMMENDATION OR FAVORING BY EPRI

THIS MATERIAL IS BASED ON WORK SUPPORTED BY THE DEPARTMENT OF ENERGY UNDER AWARD NUMBER DE-EE0002662

THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY AN AGENCY OF THE UNITED STATES GOVERNMENT NEITHER THE UNITED STATES GOVERNMENT NOR ANY AGENCY THEREOF NOR ANY OF THEIR EMPLOYEES MAKES ANY WARRANTY EXPRESS OR IMPLIED OR ASSUMES ANY LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY COMPLETENESS OR USEFULNESS OF ANY INFORMATION APPARATUS PRODUCT OR PROCESS DISCLOSED OR REPRESENTS THAT ITS USE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT PROCESS OR SERVICE BY TRADE NAME TRADEMARK MANUFACTURER OR OTHERWISE DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT RECOMMENDATION OR FAVORING BY THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF THE VIEWS AND OPINIONS OF AUTHORS EXPRESSED HEREIN DO NOT NECESSARILY STATE OR REFLECT THOSE OF THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF

THE FOLLOWING ORGANIZATIONS UNDER CONTRACT TO EPRI PREPARED THIS REPORT

University of Alaska Anchorage University of Alaska Fairbanks National Renewable Energy Laboratory

NOTE

For further information about EPRI call the EPRI Customer Assistance Center at 8003133774 or e-mail askepriepricom

Electric Power Research Institute EPRI and TOGETHERhellipSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

Copyright copy 2012 Electric Power Research Institute Inc All rights reserved

Acknowledgments

This publication is a corporate document that should be cited in the

literature in the following manner

Assessment and Mapping of the Riverine Hydrokinetic Energy Resource in the Continental

United States EPRI Palo Alto CA 2012

1026880

The following organizations under contract to the Electric Power Research Institute (EPRI) contributed to this report

University of Alaska-Anchorage3211 Providence Drive Anchorage AK 99508

Principal InvestigatorT Ravens

University of Alaska-Fairbanks3352 College RoadFairbanks AK 99775

Principal InvestigatorK Cunningham

National Renewable Energy Laboratory1617 Cole Blvd Golden CO 80401

Principal InvestigatorG Scott

This report describes research sponsored by EPRI

EPRI would like to thank participants in the expert and user groupworkshops who contributed their expertise during the course of thisproject including Donald Atwood University of Alaska Fairbanks Neil McMahon Alaska Energy Authority Kernell Reiss US Geological Survey Edward Lovelace Free Flow Power DavidMeyers US Geological Survey Wayne Jenkinson National

iii

Research Council Canada Mollie Gardner Verdant Power ClaytonBear New Energy Corporation Mary Ann Adonizio Verdant Power Sean Anderton Ocean Renewable Power Company RogerBedard EPRI (retired) Howard Hanson Florida AtlanticUniversity Tim Hogan Alden Gary Johnson Pacific Northwest National Laboratory Tim Konnert Federal Energy RegulatoryCommission John Miller University of Massachusetts-Dartmouth Brian Polagye University of Washington Mirko Previsic Re VisionConsulting Kamau Sadiki US Army Corps of Engineers LarryWeber University of Iowa

EPRI would also like to thank Hoyt Battey Caitlin Frame andBrooke White of the US Department of Energy for their interest inand contributions to this project and for initiating a review of thisproject by the National Research Council Committee on Marine andHydrokinetic Energy Technology Assessment Engagement by theDOE and the NRC has enhanced the rigor and utility of the project

iv

Product Description This report describes the methodology and results of the most

rigorous assessment to date of the riverine hydrokinetic energyresource in the contiguous 48 states and Alaska excluding tidalwaters The assessment provides estimates of the gross naturallyavailable resource termed the theoretical resource as well asestimates termed the technically recoverable resource that account for selected technological factors affecting capture and conversion ofthe theoretical resource The technically recoverable resource doesnot account for all technical constraints on energy capture andconversion

Background The US Department of Energy (DOE) funded the Electric Power Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States

Objectives The goal of this project was to estimate the riverine hydrokineticresource in the continental United States

Approach The project team derived an assessment of the hydrokinetic resource in the 48 contiguous states from spatially explicit data contained inNHDPlus a geographic information system (GIS)-based databasecontaining river segment-specific information on dischargecharacteristics and channel slope The team estimated the segment-specific theoretical resource from these data using the standardhydrological engineering equation that relates theoretical hydraulicpower (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

v

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 2: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

EPRI Project Manager P Jacobson

3420 Hillview Avenue Palo Alto CA 94304-1338

USA

PO Box 10412 Palo Alto CA 94303-0813

USA

8003133774 6508552121

askepriepricom

wwwepricom

Assessment and Mapping of the Riverine Hydrokinetic

Energy Resource in the Continental United States

1026880 Final Report December 2012

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES

THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE INC (EPRI) NEITHER EPRI ANY MEMBER OF EPRI ANY COSPONSOR THE ORGANIZATION(S) BELOW NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM

(A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER EXPRESS OR IMPLIED (I) WITH RESPECT TO THE USE OF ANY INFORMATION APPARATUS METHOD PROCESS OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS INCLUDING ANY PARTYS INTELLECTUAL PROPERTY OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USERS CIRCUMSTANCE OR

(B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION APPARATUS METHOD PROCESS OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT

REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT PROCESS OR SERVICE BY ITS TRADE NAME TRADEMARK MANUFACTURER OR OTHERWISE DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT RECOMMENDATION OR FAVORING BY EPRI

THIS MATERIAL IS BASED ON WORK SUPPORTED BY THE DEPARTMENT OF ENERGY UNDER AWARD NUMBER DE-EE0002662

THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY AN AGENCY OF THE UNITED STATES GOVERNMENT NEITHER THE UNITED STATES GOVERNMENT NOR ANY AGENCY THEREOF NOR ANY OF THEIR EMPLOYEES MAKES ANY WARRANTY EXPRESS OR IMPLIED OR ASSUMES ANY LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY COMPLETENESS OR USEFULNESS OF ANY INFORMATION APPARATUS PRODUCT OR PROCESS DISCLOSED OR REPRESENTS THAT ITS USE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT PROCESS OR SERVICE BY TRADE NAME TRADEMARK MANUFACTURER OR OTHERWISE DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT RECOMMENDATION OR FAVORING BY THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF THE VIEWS AND OPINIONS OF AUTHORS EXPRESSED HEREIN DO NOT NECESSARILY STATE OR REFLECT THOSE OF THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF

THE FOLLOWING ORGANIZATIONS UNDER CONTRACT TO EPRI PREPARED THIS REPORT

University of Alaska Anchorage University of Alaska Fairbanks National Renewable Energy Laboratory

NOTE

For further information about EPRI call the EPRI Customer Assistance Center at 8003133774 or e-mail askepriepricom

Electric Power Research Institute EPRI and TOGETHERhellipSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

Copyright copy 2012 Electric Power Research Institute Inc All rights reserved

Acknowledgments

This publication is a corporate document that should be cited in the

literature in the following manner

Assessment and Mapping of the Riverine Hydrokinetic Energy Resource in the Continental

United States EPRI Palo Alto CA 2012

1026880

The following organizations under contract to the Electric Power Research Institute (EPRI) contributed to this report

University of Alaska-Anchorage3211 Providence Drive Anchorage AK 99508

Principal InvestigatorT Ravens

University of Alaska-Fairbanks3352 College RoadFairbanks AK 99775

Principal InvestigatorK Cunningham

National Renewable Energy Laboratory1617 Cole Blvd Golden CO 80401

Principal InvestigatorG Scott

This report describes research sponsored by EPRI

EPRI would like to thank participants in the expert and user groupworkshops who contributed their expertise during the course of thisproject including Donald Atwood University of Alaska Fairbanks Neil McMahon Alaska Energy Authority Kernell Reiss US Geological Survey Edward Lovelace Free Flow Power DavidMeyers US Geological Survey Wayne Jenkinson National

iii

Research Council Canada Mollie Gardner Verdant Power ClaytonBear New Energy Corporation Mary Ann Adonizio Verdant Power Sean Anderton Ocean Renewable Power Company RogerBedard EPRI (retired) Howard Hanson Florida AtlanticUniversity Tim Hogan Alden Gary Johnson Pacific Northwest National Laboratory Tim Konnert Federal Energy RegulatoryCommission John Miller University of Massachusetts-Dartmouth Brian Polagye University of Washington Mirko Previsic Re VisionConsulting Kamau Sadiki US Army Corps of Engineers LarryWeber University of Iowa

EPRI would also like to thank Hoyt Battey Caitlin Frame andBrooke White of the US Department of Energy for their interest inand contributions to this project and for initiating a review of thisproject by the National Research Council Committee on Marine andHydrokinetic Energy Technology Assessment Engagement by theDOE and the NRC has enhanced the rigor and utility of the project

iv

Product Description This report describes the methodology and results of the most

rigorous assessment to date of the riverine hydrokinetic energyresource in the contiguous 48 states and Alaska excluding tidalwaters The assessment provides estimates of the gross naturallyavailable resource termed the theoretical resource as well asestimates termed the technically recoverable resource that account for selected technological factors affecting capture and conversion ofthe theoretical resource The technically recoverable resource doesnot account for all technical constraints on energy capture andconversion

Background The US Department of Energy (DOE) funded the Electric Power Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States

Objectives The goal of this project was to estimate the riverine hydrokineticresource in the continental United States

Approach The project team derived an assessment of the hydrokinetic resource in the 48 contiguous states from spatially explicit data contained inNHDPlus a geographic information system (GIS)-based databasecontaining river segment-specific information on dischargecharacteristics and channel slope The team estimated the segment-specific theoretical resource from these data using the standardhydrological engineering equation that relates theoretical hydraulicpower (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

v

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

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as well as experts from academia and industry to help address

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 3: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES

THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE INC (EPRI) NEITHER EPRI ANY MEMBER OF EPRI ANY COSPONSOR THE ORGANIZATION(S) BELOW NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM

(A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER EXPRESS OR IMPLIED (I) WITH RESPECT TO THE USE OF ANY INFORMATION APPARATUS METHOD PROCESS OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS INCLUDING ANY PARTYS INTELLECTUAL PROPERTY OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USERS CIRCUMSTANCE OR

(B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION APPARATUS METHOD PROCESS OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT

REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT PROCESS OR SERVICE BY ITS TRADE NAME TRADEMARK MANUFACTURER OR OTHERWISE DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT RECOMMENDATION OR FAVORING BY EPRI

THIS MATERIAL IS BASED ON WORK SUPPORTED BY THE DEPARTMENT OF ENERGY UNDER AWARD NUMBER DE-EE0002662

THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY AN AGENCY OF THE UNITED STATES GOVERNMENT NEITHER THE UNITED STATES GOVERNMENT NOR ANY AGENCY THEREOF NOR ANY OF THEIR EMPLOYEES MAKES ANY WARRANTY EXPRESS OR IMPLIED OR ASSUMES ANY LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY COMPLETENESS OR USEFULNESS OF ANY INFORMATION APPARATUS PRODUCT OR PROCESS DISCLOSED OR REPRESENTS THAT ITS USE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT PROCESS OR SERVICE BY TRADE NAME TRADEMARK MANUFACTURER OR OTHERWISE DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT RECOMMENDATION OR FAVORING BY THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF THE VIEWS AND OPINIONS OF AUTHORS EXPRESSED HEREIN DO NOT NECESSARILY STATE OR REFLECT THOSE OF THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF

THE FOLLOWING ORGANIZATIONS UNDER CONTRACT TO EPRI PREPARED THIS REPORT

University of Alaska Anchorage University of Alaska Fairbanks National Renewable Energy Laboratory

NOTE

For further information about EPRI call the EPRI Customer Assistance Center at 8003133774 or e-mail askepriepricom

Electric Power Research Institute EPRI and TOGETHERhellipSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

Copyright copy 2012 Electric Power Research Institute Inc All rights reserved

Acknowledgments

This publication is a corporate document that should be cited in the

literature in the following manner

Assessment and Mapping of the Riverine Hydrokinetic Energy Resource in the Continental

United States EPRI Palo Alto CA 2012

1026880

The following organizations under contract to the Electric Power Research Institute (EPRI) contributed to this report

University of Alaska-Anchorage3211 Providence Drive Anchorage AK 99508

Principal InvestigatorT Ravens

University of Alaska-Fairbanks3352 College RoadFairbanks AK 99775

Principal InvestigatorK Cunningham

National Renewable Energy Laboratory1617 Cole Blvd Golden CO 80401

Principal InvestigatorG Scott

This report describes research sponsored by EPRI

EPRI would like to thank participants in the expert and user groupworkshops who contributed their expertise during the course of thisproject including Donald Atwood University of Alaska Fairbanks Neil McMahon Alaska Energy Authority Kernell Reiss US Geological Survey Edward Lovelace Free Flow Power DavidMeyers US Geological Survey Wayne Jenkinson National

iii

Research Council Canada Mollie Gardner Verdant Power ClaytonBear New Energy Corporation Mary Ann Adonizio Verdant Power Sean Anderton Ocean Renewable Power Company RogerBedard EPRI (retired) Howard Hanson Florida AtlanticUniversity Tim Hogan Alden Gary Johnson Pacific Northwest National Laboratory Tim Konnert Federal Energy RegulatoryCommission John Miller University of Massachusetts-Dartmouth Brian Polagye University of Washington Mirko Previsic Re VisionConsulting Kamau Sadiki US Army Corps of Engineers LarryWeber University of Iowa

EPRI would also like to thank Hoyt Battey Caitlin Frame andBrooke White of the US Department of Energy for their interest inand contributions to this project and for initiating a review of thisproject by the National Research Council Committee on Marine andHydrokinetic Energy Technology Assessment Engagement by theDOE and the NRC has enhanced the rigor and utility of the project

iv

Product Description This report describes the methodology and results of the most

rigorous assessment to date of the riverine hydrokinetic energyresource in the contiguous 48 states and Alaska excluding tidalwaters The assessment provides estimates of the gross naturallyavailable resource termed the theoretical resource as well asestimates termed the technically recoverable resource that account for selected technological factors affecting capture and conversion ofthe theoretical resource The technically recoverable resource doesnot account for all technical constraints on energy capture andconversion

Background The US Department of Energy (DOE) funded the Electric Power Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States

Objectives The goal of this project was to estimate the riverine hydrokineticresource in the continental United States

Approach The project team derived an assessment of the hydrokinetic resource in the 48 contiguous states from spatially explicit data contained inNHDPlus a geographic information system (GIS)-based databasecontaining river segment-specific information on dischargecharacteristics and channel slope The team estimated the segment-specific theoretical resource from these data using the standardhydrological engineering equation that relates theoretical hydraulicpower (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

v

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

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as well as experts from academia and industry to help address

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 4: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Acknowledgments

This publication is a corporate document that should be cited in the

literature in the following manner

Assessment and Mapping of the Riverine Hydrokinetic Energy Resource in the Continental

United States EPRI Palo Alto CA 2012

1026880

The following organizations under contract to the Electric Power Research Institute (EPRI) contributed to this report

University of Alaska-Anchorage3211 Providence Drive Anchorage AK 99508

Principal InvestigatorT Ravens

University of Alaska-Fairbanks3352 College RoadFairbanks AK 99775

Principal InvestigatorK Cunningham

National Renewable Energy Laboratory1617 Cole Blvd Golden CO 80401

Principal InvestigatorG Scott

This report describes research sponsored by EPRI

EPRI would like to thank participants in the expert and user groupworkshops who contributed their expertise during the course of thisproject including Donald Atwood University of Alaska Fairbanks Neil McMahon Alaska Energy Authority Kernell Reiss US Geological Survey Edward Lovelace Free Flow Power DavidMeyers US Geological Survey Wayne Jenkinson National

iii

Research Council Canada Mollie Gardner Verdant Power ClaytonBear New Energy Corporation Mary Ann Adonizio Verdant Power Sean Anderton Ocean Renewable Power Company RogerBedard EPRI (retired) Howard Hanson Florida AtlanticUniversity Tim Hogan Alden Gary Johnson Pacific Northwest National Laboratory Tim Konnert Federal Energy RegulatoryCommission John Miller University of Massachusetts-Dartmouth Brian Polagye University of Washington Mirko Previsic Re VisionConsulting Kamau Sadiki US Army Corps of Engineers LarryWeber University of Iowa

EPRI would also like to thank Hoyt Battey Caitlin Frame andBrooke White of the US Department of Energy for their interest inand contributions to this project and for initiating a review of thisproject by the National Research Council Committee on Marine andHydrokinetic Energy Technology Assessment Engagement by theDOE and the NRC has enhanced the rigor and utility of the project

iv

Product Description This report describes the methodology and results of the most

rigorous assessment to date of the riverine hydrokinetic energyresource in the contiguous 48 states and Alaska excluding tidalwaters The assessment provides estimates of the gross naturallyavailable resource termed the theoretical resource as well asestimates termed the technically recoverable resource that account for selected technological factors affecting capture and conversion ofthe theoretical resource The technically recoverable resource doesnot account for all technical constraints on energy capture andconversion

Background The US Department of Energy (DOE) funded the Electric Power Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States

Objectives The goal of this project was to estimate the riverine hydrokineticresource in the continental United States

Approach The project team derived an assessment of the hydrokinetic resource in the 48 contiguous states from spatially explicit data contained inNHDPlus a geographic information system (GIS)-based databasecontaining river segment-specific information on dischargecharacteristics and channel slope The team estimated the segment-specific theoretical resource from these data using the standardhydrological engineering equation that relates theoretical hydraulicpower (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

v

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

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the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 5: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Research Council Canada Mollie Gardner Verdant Power ClaytonBear New Energy Corporation Mary Ann Adonizio Verdant Power Sean Anderton Ocean Renewable Power Company RogerBedard EPRI (retired) Howard Hanson Florida AtlanticUniversity Tim Hogan Alden Gary Johnson Pacific Northwest National Laboratory Tim Konnert Federal Energy RegulatoryCommission John Miller University of Massachusetts-Dartmouth Brian Polagye University of Washington Mirko Previsic Re VisionConsulting Kamau Sadiki US Army Corps of Engineers LarryWeber University of Iowa

EPRI would also like to thank Hoyt Battey Caitlin Frame andBrooke White of the US Department of Energy for their interest inand contributions to this project and for initiating a review of thisproject by the National Research Council Committee on Marine andHydrokinetic Energy Technology Assessment Engagement by theDOE and the NRC has enhanced the rigor and utility of the project

iv

Product Description This report describes the methodology and results of the most

rigorous assessment to date of the riverine hydrokinetic energyresource in the contiguous 48 states and Alaska excluding tidalwaters The assessment provides estimates of the gross naturallyavailable resource termed the theoretical resource as well asestimates termed the technically recoverable resource that account for selected technological factors affecting capture and conversion ofthe theoretical resource The technically recoverable resource doesnot account for all technical constraints on energy capture andconversion

Background The US Department of Energy (DOE) funded the Electric Power Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States

Objectives The goal of this project was to estimate the riverine hydrokineticresource in the continental United States

Approach The project team derived an assessment of the hydrokinetic resource in the 48 contiguous states from spatially explicit data contained inNHDPlus a geographic information system (GIS)-based databasecontaining river segment-specific information on dischargecharacteristics and channel slope The team estimated the segment-specific theoretical resource from these data using the standardhydrological engineering equation that relates theoretical hydraulicpower (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

v

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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the United States and international participation extends to more than

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Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 6: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Product Description This report describes the methodology and results of the most

rigorous assessment to date of the riverine hydrokinetic energyresource in the contiguous 48 states and Alaska excluding tidalwaters The assessment provides estimates of the gross naturallyavailable resource termed the theoretical resource as well asestimates termed the technically recoverable resource that account for selected technological factors affecting capture and conversion ofthe theoretical resource The technically recoverable resource doesnot account for all technical constraints on energy capture andconversion

Background The US Department of Energy (DOE) funded the Electric Power Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States

Objectives The goal of this project was to estimate the riverine hydrokineticresource in the continental United States

Approach The project team derived an assessment of the hydrokinetic resource in the 48 contiguous states from spatially explicit data contained inNHDPlus a geographic information system (GIS)-based databasecontaining river segment-specific information on dischargecharacteristics and channel slope The team estimated the segment-specific theoretical resource from these data using the standardhydrological engineering equation that relates theoretical hydraulicpower (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

v

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

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as well as experts from academia and industry to help address

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analyses to drive long-range research and development planning and

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the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 7: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

For Alaska which is not encompassed by NHDPlus the teammanually obtained hydraulic head and discharge data from IdahoNational Laboratoryrsquos Virtual Hydropower Prospector GoogleEarth and US Geological Survey gages The team estimated thetechnically recoverable resource by applying a recovery factor to thesegment-specific theoretical resource estimates This analysis whichincluded 32 scenarios led to an empirical function relating recoveryfactor to slope and discharge For Alaska where data on river slopewas not readily available the recovery factor was estimated based onthe flow rate alone

Results Segment-specific theoretical resource aggregated by major hydrologic region in the contiguous lower 48 states totaled 1146TWhyr The aggregate estimate of the Alaska theoretical resource is 235 TWhyr yielding a total theoretical resource estimate of 1381TWhyr for the continental United States The technicallyrecoverable resource estimate for the continental United States is 120 TWhyr

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results areonly available for the 48 contiguous states Alaska will be added in the future

Applications Values and Use While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deploymentwould further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions and highly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Keywords Hydrokinetic resourcesHydropowerRenewable resources

vi

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 8: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Executive Summary The US Department of Energy (DOE) funded the Electric Power

Research Institute and its collaborative partners University of Alaskandash Anchorage University of Alaska ndash Fairbanks and the NationalRenewable Energy Laboratory to provide an assessment of theriverine hydrokinetic resource in the continental United States Theassessment benefited from input obtained during two workshopsattended by individuals with relevant expertise and from a National Research Council panel commissioned by DOE to provide guidanceto this and other concurrent DOE-funded assessments of water-based renewable energy These sources of expertise provided valuable advice regarding data sources and assessment methodology

The assessment of the hydrokinetic resource in the 48 contiguousstates is derived from spatially-explicit data contained in NHDPlus ndash a GIS-based database containing river segment-specific informationon discharge characteristics and channel slope 71398 river segmentswith mean annual flow greater than 1000 cubic feet per second (cfs) mean discharge were included in the assessment Segments withdischarge less than 1000 cfs were dropped from the assessment aswere river segments with hydroelectric dams The results for thetheoretical and technical resource in the 48 contiguous states werefound to be relatively insensitive to the cutoff chosen Raising thecutoff to 1500 cfs had no effect on estimate of the technicallyrecoverable resource and the theoretical resource was reduced by53

The segment-specific theoretical resource was estimated from thesedata using the standard hydrological engineering equation thatrelates theoretical hydraulic power (Pth Watts) to discharge (Q m3 s-1) and hydraulic head or change in elevation (∆119867 m) over the length of the segment where 120574 is the specific weight of water (9800 N m-3)

119875119905ℎ = 120574 119876 ∆119867

For Alaska which is not encompassed by NPDPlus hydraulic headand discharge data were manually obtained from Idaho NationalLaboratoryrsquos Virtual Hydropower Prospector Google Earth andUS Geological Survey gages Data were manually obtained for theeleven largest rivers with average flow rates greater than 10000 cfsand the resulting estimate of the theoretical resource was expanded to

vii

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 9: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

include rivers with discharge between 1000 cfs and 10000 cfs basedupon the contribution of rivers in the latter flow class to the totalestimate in the contiguous 48 states

Segment-specific theoretical resource was aggregated by major hydrologic region in the contiguous lower 48 states (Table ES-1) and totaled 1146 TWhyr The aggregate estimate of the Alaskatheoretical resource is 235 TWhyr yielding a total theoreticalresource estimate of 1381 TWhyr for the continental US

The technically recoverable resource in the contiguous 48 states wasestimated by applying a recovery factor to the segment-specific theoretical resource estimates The recovery factor scales thetheoretical resource for a given segment to take into account assumptions such as minimum required water velocity and depthduring low flow conditions maximum device packing density deviceefficiency and flow statistics (eg the 5 percentile flow relative tothe average flow rate) The recovery factor also takes account of ldquobackeffectsrdquo ndash feedback effects of turbine presence on hydraulic head andvelocity The recovery factor was determined over a range of flowrates and slopes using the hydraulic model HEC-RAS In the hydraulic modeling presence of turbines was accounted for byadjusting the Manning coefficient This analysis which included 32scenarios led to an empirical function relating recovery factor toslope and discharge Sixty-nine percent of NHDPlus segmentsincluded in the theoretical resource estimate for the contiguous 48states had an estimated recovery factor of zero For Alaska data onriver slope was not readily available hence the recovery factor wasestimated based on the flow rate alone Segment-specific estimatesof the theoretical resource were multiplied by the correspondingrecovery factor to estimate the technically recoverable resource The resulting technically recoverable resource estimate for the continentalUnited States is 120 TWhyr (Table 1)

viii

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 10: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 1 Theoretical and technically recoverable hydrokinetic energy estimates for the continental United States

Hydrologic Region

Theoretical Power (Annual Energy

TWhyr)

Technically Recoverable

Power (Annual Energy TWhyr)

New England 144 02

Mid Atlantic 335 10

South Atlantic Gulf 385 12

Great Lakes 62 001

Ohio 792 69

Tennessee 204 10

Sauris Red-Rainy 18 003

Upper Mississippi 470 51

Lower Mississippi 2088 574

Texas Gulf 89 005

Arkansas Red 451 13

Lower Missouri 798 56

Upper Missouri 743 28

Rio Grande 295 03

Lower Colorado 576 39

Upper Colorado 469 11

Great Basin 69 0

California 509 07

Pacific Northwest 2967 110

Alaska 235 205

Total 1381 1199

The Lower Mississippi region contributes nearly half (479) of thetotal resource estimate The major rivers of Alaska constitute 171of the total for the continental US The next largest contributor isthe Pacific Northwest region which contributes 92 followed bythe Ohio region (57) Collectively these four regions encompass80 of the technically recoverable hydrokinetic resource in thecontinental US

ix

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

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as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

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analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 11: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

While the calculation of the technically recoverable hydrokineticresource takes into account some important constraints a fuller accounting of additional practical constraints on turbine deployment would further reduce the portion of the theoretical resource that isestimated to be recoverable The practically recoverable resourceremains an unknown ndash and perhaps small -- portion of thetechnically recoverable resource Additional data assumptions andhighly detailed analysis are required to reliably estimate thepractically recoverable hydrokinetic resource

Results of this study can be geo-spatially visualized queried and downloaded from the National Renewable Energy Laboratoryrsquos website at httpmapsnrelgovriver_atlas Currently results are only available for the 48 contiguous states Alaska will be added in the future

x

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 12: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table of Contents

Section 1 Introduction and Background 1-1 Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource 1-2

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource2-1

Contiguous 48 States 2-1 Preparing the Data2-3 Alaska 2-5

Section 3 Results for Theoretically Available Hydrokinetic Resource3-1

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource4-1

Section 5 Results for the Technically Recoverable Hydrokinetic Resource5-1

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource6-1

Section 7 GIS Display 7-1 Data Processing 7-1 Tool Functionality and Capabilities7-1 Application Analysis7-2 Intended Audience 7-2

Section 8 Conclusions8-1

Appendix A Validation A-1

xi

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 13: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Appendix B Hydraulic Impacts of Hydrokinetic Devices B-1

Abstract B-1 Introduction B-1 Analysis B-2

Representation of hydrokinetic devices with an enhanced bottom roughness B-3 Channel energy losses due to presence of

Determination of the effective Manningrsquos roughness

Example calculation of the hydraulic impact of a

Hydraulic impacts of HK devices associated with

hydrokinetic devicesB-4 Determination of water depth with devices present B-5

coefficient and velocity with devices present B-6

uniform distribution of hydrokinetic devicesB-6

deployments in spatially limited areas B-8 Notation B-11

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska C-1

Appendix D References D-1

xii

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 14: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

List of Figures

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis 2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run) 2-3

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated2-4

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region 2-7

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas 4-4

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot) 4-8

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43 4-9

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US 6-2

xiii

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 15: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Figure B-1 Plot of normalized depth (hth) normalized velocity (VtV) normalized effective Manning roughness (ntn) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio as a function of density of hydrokinetic devices (number of devices per 10 D m length) B-7

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devicesB-9

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devicesB-10

xiv

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 16: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

List of Tables

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study 2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study 2-6

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska 3-1

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s) 4-3

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005 4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data4-7

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska 5-1

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth 6-1

Table 6-2 Sensitivity of Recovery Factor calculation 6-4

Table A-1 Top Rivers by Power Production A-2

Table B-1 Channel flow and turbine properties assumed in example calculation B-7

Table B-2 Channel flow and turbine properties assumed B-8

xv

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 17: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s) C-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs C-6

xvi

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 18: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 1 Introduction and Background This report describes the methodology and results of the most rigorousassessment to date of the riverine hydrokinetic energy resource in the contiguous48 states and Alaska excluding tidal waters The assessment provides estimatesof the gross naturally available resource termed the theoretical resource as wellas estimates termed the technically recoverable resource that account for selectedtechnological factors affecting capture and conversion of the theoretical resourceThe technically recoverable resource as defined in this study does not account for all technical constraints on energy capture and conversion

The practical resource ndash the resource that could be recovered consideringadditional factors such as existing uses environmentally sensitive and otherexclusion areas economic constraints and access to load or transmission ndash is anunknown fraction of the technically recoverable resource This report does not provide an assessment of the practical resource nor does it provide theinformation needed to site projects Far more detailed study is required toestimate the practical resource and to select candidate sites for hydrokineticproject development

This report is intended to provide policymakers project developers hydrokineticenergy device developers investors universities non-governmental organizations environmental groups the US Department of Energy (DOE) the military and the US Army Corps of Engineers and the US Geological Survey an assessmentof the general magnitude and geographic distribution of the riverine hydrokineticresource across the continental United States

The DOE previously commissioned a study of the US hydrokinetic energyresource (Miller et al 1986) That study derived estimates of hydrokinetic power for selected river segments in 12 of 16 hydrologic regions of the US with meandischarge of at least 4000 cubic feet per second (cfs) and velocity greater than 43feet per second (fps) Within each of the regions in which these criteria weremet the rivers with the greatest potential were selected for assessment This procedure provided estimates of recoverable power in the rivers with the greatestpotential in each of the regions meeting the minimum criteria however thecriteria for inclusion in the study differed among regions Recoverable power wasestimated assuming turbine deployment in 25 of the estimated width and 25of river segment lengths meeting the minimum discharge criteria turbinediameter equal to 80 of the mean depth turbine spacing of half a turbinediameter space between turbines in each row and 5 turbine diameters spacingbetween rows and system efficiency of 40 Miller et al (1986) did not include

1-1

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

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as well as experts from academia and industry to help address

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the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 19: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

the feedback effects of turbine deployment on water velocity The foregoingmethodology applied to the selected river segments yielded an aggregate powerestimate slightly greater than 12500 MW average annual power (110 TWhyr) There are no other broad-scale riverine hydrokinetic resource assessments for the United States Canada is currently conducting an assessment of its riverinehydrokinetic resource (NRC-CHC 2010)

The present assessment improves upon the estimate of Miller et al (1986) in a number of ways It includes the potential energy associated with hydraulic headas well as the back effects of turbine deployment It also applies a consistent criterion for inclusion across the contiguous 48 states and explicitly assesses alarger number of rivers in Alaska The threshold for inclusion in this assessment is 1000 cfs mean discharge making the present assessment more comprehensive in its scope This assessment however makes different assumptions regardingturbine deployment leading to a flow threshold for hydrokinetic energy recoveryof 7000 cfs mean discharge

The choice of databases selected for this study as well as the underlyingmethodology and analytical assumptions benefited from advice acquired in twoexpert workshops The project also benefited from review and input by acommittee of the National Research Council that was commissioned by DOE to review this resource assessment and the related DOE-funded assessments ofother water-based resource types

Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource

The in-stream (non-tidal) hydrokinetic power theoretically available in a given river segment (Pth Watts) is defined

119875119905ℎ = 120574 119876 ∆119867 Eq 1-1

where 120574 is the specific weight of water (~9800 N m-3)

Q is the flow rate (m3s) and ∆119867 (m) is the change in hydraulic head between the beginning and end of the river segment

The in-stream hydrokinetic power technically recoverable in a given river segment (Ptech Watts) is the portion of the theoretically available power that can berecovered given selected technical constraints and assumptions including

a) water depth at the 5-percentile flow (the flow exceeded 95 of the time)greater than or equal to 20 m

b) depth-averaged velocity of the 5-percentile flow greater than or equal to 05ms

1-2

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 20: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

c) ldquorule-of-thumbrdquo device spacing and d) 30 ldquowater to wirerdquo device efficiency including efficiencies of rotor gearbox

generator frequency converter and step-up transformer (EPRI 2008)

The technically available hydrokinetic power estimates incorporate ldquoback effectsrdquondash feedback effects of energy extraction on river depth and velocity Section 4 provides a detailed description of the methodology used to estimate the technically recoverable resource

1-3

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

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nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 21: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource

This section describes the methodology for estimating the theoretically availablenon-tidal riverine hydrokinetic resource Consultation with an expert panelconvened in April 2010 to support this assessment identified NHDPlus as themost suitable hydrography dataset for assessment of the hydrokinetic resource Currently the NHDPlus database covers the 48 contiguous states but does not encompass Alaska consequently a different data source and methodology are required for the State of Alaska NHDPlus is described briefly below Additional information and documentation is available at wwwhorizonshysystemscomnhdplus

Contiguous 48 States

Mapping data exists to estimate the available power from the rivers in thecontiguous United States This mapping data is in the form of a geographicinformation system (GIS) and is part of the US National Map developed by theUS Geological Survey (USGS) The GIS layer of the US National Map withriver data is the National Hydrography Dataset (NHD) In addition to rivers NHD includes other hydrographic features such as shorelines lakes and pondsas well as canals and aqueducts

The Environmental Protection Agency (EPA) collaborated with the USGS toenhance NHD to support EPArsquos water quality modeling activities The enhanced GIS database called NHDPlus represents hydrologic networks as networks of ldquoflowlinesrdquo Individual flowlines range in length from 1m to 41km and each has an assigned average velocity discharge and slope These flowlinesand associated data constitute the basic geo-spatial units of analysis for theportion of this study encompassing the 48 contiguous states We use the term segments to refer to these geo-spatial units of analysis

Figure 21 below shows NHDPlus flowlines for the Mississippi Missouri andIllinois rivers at St Louis Missouri overlaid on a map of the area The arrowhead at the bottom of each flowline indicates the direction of flow This exampleillustrates discrepancies between the flowlines in NHDPlus and river coursesdepicted in a more recent map

2-1

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 22: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Figure 2-1 Flowlines of various lengths and downstream directions near St Louis

Theoretical power is estimated according to Equation 11 using the segment-specific average water discharge (Q) provided by NHDPlus in units of cubic feetper second (cfs) Hydraulic head (ΔH) is calculated from segment length and slope Figure 22 shows GIS data for a number of NHDPlus flowlines(segments) NHDPlus provides two estimates of annual discharge but only one(MAFLOWU) is available in all of the river segments Hence the ldquoMAFLOWUrdquo estimate of discharge is used in this study

2-2

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 23: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Figure 2-2 Screenshot of NHDPlus data showing flowline identifier (FID) Geographic Names Information System ID (GNIS_ID) river name (GNIS_NAME) length (LENGTHKM km) computed mean annual flow (MAFLOWU cfs) and average slope (SLOPE unitless rise over run)

Preparing the Data

This assessment is limited to the riverine hydrokinetic resource thus NHDPlusrecords pertaining to lakes reservoirs ponds etc are excluded from the analysis Smaller rivers and stream segments with discharge of less than 1000 cubic feetper second (cfs) are also excluded The minimum flow criterion was selected in consultation with the expert panel convened on April 27 2011

Segments containing dams with hydroelectric plants were also excluded from analysis Existing hydroelectric generating facilities for the analysis weredetermined using licensed data from the Homeland Security InfrastructureProgram (HSIP) Hydroelectric plants were spatially referenced by featureintersection with the NHDPlus data using a 025 mile buffer around the HSIPhydroelectric plants River segments that were intersected within the buffer wereanalyzed by their delta-H attribute (difference in elevation between segmentendpoints) and ranked in order from largest to smallest The river segments withthe largest delta-H values from each hydroelectric plant buffer area were selectedas the segment most likely to contain the dam A limited number of

2-3

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 24: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

hydroelectric dams were not included in the results of initial spatial analysis mostoften due to distances greater than 025 miles between the power house and theoriginal river channel that was used to map the river in-stream data These occurrences were handled by comparing the HSIP Electric Power Plant locationswith the publically available National Inventory of Dams (NID) data locationsWhere applicable the search bounds were increased to intersect these locationswith the river in-stream data The same methodology from the initial analysiswas applied to the intersected river segments within the increased search area forselecting the river segment with the greatest delta-H attribute These segmentswere appended to the results from the initial spatial analysis and all segmentsidentified in this manner were excluded from the resource assessment

These exclusionary criteria reduced the number of NHDPlus records from 29million to 71398 records Figure 23 shows the rivers with mean discharge greater than 1000 cfs in the contiguous United States which are included in theassessment and the hydrologic basins by which results are aggregated for presentation Note that several of the basins extend north into Canada and south into Mexico however those areas were excluded from the analysis

Figure 2-3 Riverine resources and hydrographic regions for which the theoretical power is calculated

2-4

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

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as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

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Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

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copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 25: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Alaska

Since NHDPlus does not encompass Alaska alternative sources were used toobtain input values for the theoretical power equation (120574119876∆119867) Averagedischarge data was obtained from USGS gages to the extent possible WhereUSGS gage data was lacking we obtained average discharge data from theVirtual Hydropower Prospector (the Prospector) developed for Alaska by theIdaho National Laboratory(httphydropowerinelgovprospectorindexshtml) The discharge datafrom the Prospector and USGS gages at selected sites was generally similar Table 21 compares discharge data from the Prospector and from USGS gages at four examples sites On average the Prospectorrsquos estimate of annual averagedischarge was 25 higher than that based on USGS measurements By far thedeviation between the Prospector discharge estimate and the USGSmeasurement was greatest at Eagle on the Yukon River Ignoring this outlier theProspector estimate was within 10 of the USGS measurement USGS discharge measurements were used for the estimate of the theoretical resource in the Yukon River

Table 2-1 Analysis of discharge data from the Prospector and from USGS gages for the Alaska portion of the study

Location River Prospector USGS Difference

(cfs) (cfs)

Eagle Yukon 148100 84000 763

Crooked Creek Kuskokwim 54300 42000 293

Hughes Koyukuk 14800 14600 14

Million Dollar Bridge Copper 61300 61900 -10

Average 265

Hydraulic head change in the river segments was estimated based on river surface elevations from the Prospector or from Google Earth A comparison of surfaceelevations from the Prospector and Google Earth indicated they yield similarresults (Table 22) The discharge at the segment ends (which differedsignificantly in some instances) was averaged to obtain the segment discharge for the theoretical power calculation

2-5

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

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as well as experts from academia and industry to help address

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copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 26: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 2-2 Analysis of elevation change data from Google Earth and from the Prospector for the Alaska portion of the study

Elevation Elevation Difference from Difference from

Segment Segment Google Earth the Prospector Percent Start End (m) (m) Difference

Eagle Yukon River

Stevens Village Yukon River

2244 2211 1

Crooked Creek Kuskokwim River

Bethel Kuskokwim River

412 404 2

Talkeetna Susitna River

Mouth of Susitna River Cook Inlet

997 1070 -7

This methodology was first used to estimate the theoretical power for segmentswith mean discharge exceeding approximately 10000 cfs in the following majorrivers Yukon

Porcupine Kuskokwim Tanana

Susitna Colville Stikine

Kvichak Nushagak Noatak

Copper

In order to estimate the theoretical resource in Alaska for flows between 1000 cfsand 10000 cfs an analysis of the contribution to the theoretical resource fromsegments with discharge above and below 10000 cfs was conducted for the 19hydrologic regions in the NHDPlus database (which was available for thecontiguous US) For each of the 19 regions in the NHDPlus database the ratioof the theoretical power from flows above 10000 cfs to power from flows above1000 (R100001000) was determined Further that ratio was examined as a functionof the maximum annual flow rate in the region (Figure 24) It was anticipatedthat regions with very large rivers (eg the Lower Mississippi) would have arelatively large fraction of its theoretical resource coming from segments withflow rate above 10000 cfs Hence R100001000 would be quite high approaching 1The data in Figure 24 confirms this idea Based on the logarithmic regressionequation in the figure and given a maximum annual discharge in Alaska of

2-6

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 27: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

272000 cfs R100001000 for Alaska was estimated to be 075 Finally thetheoretical resource (for Q gt 1000 cfs) was estimated to be 133 times thetheoretical resource for discharges greater than 10000 cfs

y = 01884ln(x) - 15713 Rsup2 = 05613

0

02

04

06

08

1

12

0 100000 200000 300000 400000 500000 600000 700000 800000

R 10

000

100

0

flow rate (cfs)

Figure 2-4 Ratio of the theoretical power from flows above 10000 cfs to power from flows above 1000 (R100001000) for the 19 hydrologic regions of the contiguous US as a function of maximum annual discharge rate in that region

An alternative estimate of R100001000 for Alaska would be to ignore thedependence of the ratio on discharge and simply determine R100001000 consideringall of the regions of the contiguous US In that case the ratio would be 0615 andthe aggregate estimate for Alaska segments with discharge exceeding 10000 cfswould be multiplied by 163 to obtain an estimate of statewide theoretical power in segments exceeding 1000 cfs Given the relatively high R2 value in Figure 24 the former approach was adopted

2-7

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 28: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 3 Results for Theoretically Available Hydrokinetic Resource

The estimate of the theoretical resource for the continental United States (contiguous 48 states and Alaska) totals 1381 TWhyr (Table 31) Collectively the Pacific Northwest Lower Mississippi and Alaska regions comprise 54 of the total estimated theoretical resource Appendix C reports the theoreticalresource estimates for the major rivers in Alaska Expansion of the resultsdetailed in Appendix C to account for the theoretical power in rivers of dischargebetween 10000 and 1000 cfs as described in Section 2 yields a total Alaska resource estimate of approximately 235 TWhyr The Yukon River had atheoretical resource of 805 TWhyr and was the largest contributor to Alaskarsquos hydrokinetic power potential

Table 3-1 Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Hydrologic Region Theoretical Power

(Annual Energy TWhyr)

New England 144

Mid Atlantic 335

South Atlantic Gulf 385

Great Lakes 62

Ohio 792

Tennessee 204

Sauris Red-Rainy 18

Upper Mississippi 470

Lower Mississippi 2088

Texas Gulf 89

Arkansas Red 451

Lower Missouri 798

3-1

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 29: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 3-1 (continued) Theoretical power (annual energy) presented in units of terawatt hours per year aggregated by hydrologic regions that are depicted in Figure 31 and Alaska

Theoretical Power Hydrologic Region (Annual Energy TWhyr)

Upper Missouri 743

Rio Grande 295

Lower Colorado 576

Upper Colorado 469

Great Basin 69

California 509

Pacific Northwest 2967

Alaska 235

Total 1381

3-2

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 30: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource

The technically recoverable in-stream hydrokinetic resource can be broadlydefined as the amount of power that could be recovered given existing technologies The technically recoverable resource is operationally defined by themethodology for estimating the fraction of the theoretically available resourcethat is technically recoverable We refer to the scalar applied to the theoreticalresource as the ldquorecovery factorrdquo The recovery factor which is a function of theriver slope and average discharge was evaluated and applied by river segment The technically recoverable resource was determined by assigning a recoveryfactor to each river segment in the database and determining the product of therecovery factor and the theoretical resource and summing across segments

A number of studies and reviews address the recoverable hydrokinetic resource intidal settings (eg Couch and Bryden 2004 Garrett and Cummins 2005 Bryden and Couch 2006 EPRI 2006 Garrett and Cummins 2007 Lunden and Bahaj2007 Sutherland et al 2007 Blanchfield et al 2008 Garrett and Cummins 2008 Karsten et al 2008 Polagye et al 2008 Sun et al 2008 Walkington and Burrows2009 Atwater and Lawrence 2010 Shapiro 2010 Defne et al 2011 Yang and Wang 2011) however there is no known definitive study published on therecoverable river in-stream hydrokinetic resource other than the 1986 study by Miller et al Ortgega-Achury et al (2010) specifically addressed riverinehydrokinetics as well as other hydrokinetic technologies but focused on thehydraulic and environmental consequences of turbine deployment rather than on the amount of recoverable energy in rivers

One of the first studies to address energy extraction in a tidal context (Garrettand Cummins 2005) examined a constricted channel connecting two large bodiesof water in which the tides at both ends were assumed to be unaffected by thecurrents through the channel The turbines were assumed to be a uniform ldquofencerdquodeployed across the channel By assuming the water level difference betweenchannel entrance and exit to be a cos wt (where w is the angular frequency and a is the tidal amplitude) Garrett and Cummins determined a maximum average power available of approximately 022γaQmax where Qmax is the maximum volumetric discharge in the channel (with no devices present) Given theresemblance of the Garrett and Cummins expression to our equation for the

4-1

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 31: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

theoretical resource (Eq 11) it would be tempting to assume that 22 of theriverine theoretical resource is recoverable That is 022 might be taken as a first estimate of the riverine recovery factor The nature of tidal and riverine channels and their respective flows however are fundamentally different For exampleunsteady flow and flow acceleration are critically important characteristics of tidalflow Furthermore in their treatment of the tidal problem Garrett andCummins (2005) included flow separation as the flow exits the channel Riverine channel flow however readily can be treated as steady non-accelerating flowwithout flow separation issues Tidal and riverine flows also differ verydramatically in the way they will respond to deployments of increasing numbersof hydrokinetic devices Garrett and Cummins (2005) explain that in tidal channels the discharge tends to decrease as the number of devices becomesexcessively large In contrast discharge is independent of the number (or density) of devices deployed in a riverine channel Finally while Garrett andCummins (2005) establish the theoretical resource for a tidal system under theconditions assumed it does not address the technically recoverable energy byaccounting for factors such as minimum flow depths and velocities and spatialconstraints on turbine deployment

This project determines the recovery factor for riverine channels based onfundamental river hydraulic principles and incorporates realistic depth velocity and device spacing constraints developed in consultation with device and projectdevelopers

The recovery factor methodology assumes a simplified geometry ndash a ldquoVrdquo shapedriver cross-section ndash with a side-slope of 006 based on the measured cross-river geometries of 21 river cross-sections (4 from the Mississippi River 5 from theColumbia River 3 from the Snake River 4 from the Connecticut River 2 fromthe Savannah River 2 from the Willamette River and 1 from the KuskokwimRiver) Assuming a V-shaped channel and a single side slope value is somewhatarbitrary however the sensitivity study described in Section 6 indicates that therecovery factor is relatively insensitive to side slope The recovery factormethodology also assumes a cumulative distribution function for ldquonormalizedrdquodischarge (discharge divided by the average discharge) The cumulativedistribution function for normalized discharge was based on USGS statistics for the Mississippi River at Vicksburg Mississippi (Table 41) Flow statistics from alower Mississippi River gage were chosen since the lower Mississippi is thedominant source of US hydrokinetic energy River bottom roughness isrepresented using a Manning roughness coefficient (n) of 003 s m-13

4-2

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 32: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 4-1 Discharge statistics assumed for recovery factor calculations based on measured discharge statistics from Vicksburg on the Mississippi River The normalized discharge is the discharge relative to the annual average (17000 m3s)

Discharge percentile Normalized Discharge

5 018

25 034

50 060

75 118

95 318

Recovery Factors were calculated for selected combinations of 7 river slopes(0005 0002 0001 00005 00003 00001 000002) and 7 discharges (2000010000 3000 1000 400 200 and 100 m3s Table 42) in three steps First thepower theoretically available over a 1000 m length of channel was determinedusing Eq 1 from Section 2 (119875119905ℎ = 120574 119876 ∆119867) Next the technically recoverablepower was determined (following the procedure described below) Finally theratio of the technically recoverable to theoretically available power wasdetermined Note that not all 49 combinations of discharge and slope wereevaluated Some scenarios were skipped either because it was clear prior toevaluation that they were well outside of the envelope of conditions suitable forturbine deployment (ie too shallow) or because they constituted unrealistic or rare conditions (eg high slope in combination with high discharge)

The technically recoverable power was determined using a HEC-RAS flowmodel The first step was to determine the portion of the channel cross-sectionin which flow velocity and depth would be sufficient for hydrokinetic devicedeployment An expert panel convened in Washington DC during April 2011advised that velocity and depth should exceed 05 ms and 2 m respectivelyduring low (5th percentile) flow conditions Using the idealized (ldquoVrdquo shaped)channel the distribution of velocity and water depth for the 5-percentile flow(Q5) was calculated using the HEC-RAS model Figure 41 below shows anexample calculation of the distribution of velocity and depth for Q5 = 1800 m3sand river slope = 00001 The average flow rate was 10000 m3s Areas of insufficient depth (h5 lt 2 m) or insufficient velocity (V5 lt 05 ms) were designated in HEC-RAS as the ldquoleft bankrdquo and ldquoright bankrdquo Here h5 and V5

refer to the 5-percentile depth and depth-averaged velocity respectively

4-3

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

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Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 33: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Figure 4-1 Display of calculated velocity and depth in idealized ldquoV-shapedrdquo channel for Q5 = 1800 m3s and river slope = 00001 The red dots indicate the left and right bank areas

Secondly hydrokinetic devices were deployed (virtually) in the portion of theriver cross-section with sufficient depth and velocity (ie between the red dots inFigure 41) Note in this instance deployment in the left and right bank areas isrestricted due to depth limitations The devices were deployed according to ldquoruleof thumbrdquo spacing Specifically it was assumed that devices would be deployed inrows Rows of devices were separated by a distance of 10 D where D is the devicediameter Devices in a given row were separated by 2 D The device diameter wasassumed to be 80 of the average depth in deployment area (at the 5 percentile flow) The presence of the hydrokinetic devices would slow the flow of water inthe channel (ie cause ldquoback effectsrdquo) To determine these back effects thepresence of hydrokinetic devices was represented within HEC-RAS bycomputing an effective bottom-roughness The effective roughness (referred to as nt) was determined based on the roughness of the natural channel bottom (n) the energy extraction of the hydrokinetic devices and additional energy lossesassociated with the mixing of the low velocity wake water with high velocitywater outside the wake Based on a series of hydraulic calculations (Appendix BKartezhnikova and Ravens in review) it was determined that

119899119905 = 119899 middot 11988713 minus 028263 middot 119887minus13 + 0139296 53 Eq 4-1

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

120585 (1+ϵ) 119873119860119903a = 3 ∙ ∙ ℎ13 4 1198992119892 119908119871

4-4

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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the United States and international participation extends to more than

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Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

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copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 34: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

120585 is device efficiency

ϵ is blockage ratio (fraction of river cross-section occupied by devices)

N is the number of devices in the river segment under consideration

Ar (m2) is the frontal (or swept) area of the device

h (m) is water depth

w (m) is the width of the river or channel that is occupied by devices and

L (m) is the segment length

Note recent research (Ravens et al in preparation) has shown that hydraulicimpacts of hydrokinetic device deployments ndash as calculated using the enhancedroughness approach ndash are in agreement with hydraulic impacts as calculated usingEFDC-based software developed by Sandia Labs (Jesse Roberts Sandia National Laboratory personal communication) Using the enhanced bottom roughness (nt) to represent the devices the average velocity (V ms) in the device deployment area was computed for the 5- 25- 50- 75- and 95-percentile flowrates (Table 41) In addition the extracted power (ie technically availablepower) for each flow rate was calculated using

119875119905119890119888ℎ = 120585 1205882 1198813(119873119860119903) Eq 4-2

Finally the ratio of the technically recoverable power to theoretically availablepower (ie the recovery factor) was calculated for each discharge The recoveryfactor at a given river segment was observed to decrease with increasingdischarge For example the recovery factor for the various discharges is providedfor a channel with an average discharge of 10000 and for a slope of 00005 (Table 42) The weighted average recovery factor is 024 which is approximatedby the recovery factor for the 50-percentile discharge Table 42 also reports theaverage flow depth in the deployment area with and without hydrokinetic devicesdeployed The data shows that the impact of the devices on water level increaseswith flow rate Finally Table 42 shows how the blockage ratio ndash the ratio of theturbine swept area to the cross-sectional area - varies with flow rate (at a givenlocation) Three calculations of blockage ratio are provided in Table 42

4-5

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 35: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 4-2 Variation of Recovery Factor with discharge for a V-shaped channel with an annual average flow rate of 10000 m3s and a slope of 00005

Flow percentile Q5 Q25 Q50 Q75 Q95

Flow rate (m3s) 1800 3400 6000 11800 31800

Recovery Factor 028 027 024 021 016

Average depth (m) in deployment area with no devices 468 659 880 1219 191

Average depth (m) in deployment area with devices 579 796 1040 1403 2126

Blockage ratio in deployment area neglecting back effects 0209 0148 0111 0080 0051

Blockage ratio in deployment area accounting for back effects 0169 0123 0094 0070 0046

Blockage ratio in the river cross-section accounting for back effects 0147 0093 0061 0038 0018

The recovery factors for 32 flow and slope scenarios are provided in Table 43 The recovery factors in Table 43 were estimated based on the recovery factor for the 50-percentile flow Table 43 also displays the average water depth in thedeployment area with and without devices at the 50-percentile flow rate for selected scenarios The data shows that the impact of devices is greatest when thedischarge is greatest

4-6

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 36: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 4-3 Discharge - river slope scenarios and recovery factor calculation results ND= no data

Slope

Average depth (m) Average depth Annual in deployment (m) in deployment

average flow Recovery area with no area with devices rate (m3s) factor devices (at Q50) (at Q50)

10000 0001 023 ND ND 3000 0001 017 ND ND

3000 0005 013 ND ND 1000 0005 0 - -

10000 0002 022 ND ND 3000 0002 016 ND ND 1000 0002 007 361 377

700 0002 003 33 336 400 0002 0 - -

1000 0001 009 40 423 700 0001 006 363 379 400 0001 0 - -

10000 00005 024 880 1040 3000 00005 019 604 684 1000 00005 012 439 474

400 00005 004 345 355 200 00005 0 - -

20000 00003 027 1214 1478 10000 00003 025 959 1142

1000 00003 014 468 511 500 00003 009 388 410 200 00003 0 - -

20000 00001 028 1464 1767 10000 00001 027 1152 140

1000 00001 018 552 620 200 00001 004 352 358 100 00001 0 - -

20000 000002 024 2163 2588 10000 000002 023 1696 1985

3000 000002 009 1194 1238 1000 000002 002 859 864

100 000002 0 - -

4-7

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 37: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Based on these data an expression was developed to relate recovery factor (RF) to annual average flow rate (Q m3s) and slope (S)

minus(119871119900119892(119878)minus1498)20002647(119876minus200)03426

119877119865 = 119890 1987 119894119891 119876 gt 200 Eq 4-3 radic624277 1198782

119877119865 = 0 119894119891 119876 le 200

This expression explains 88 of the variance in recovery factor for the set ofscenarios in Table 43 Two viewpoints of a surface plot of the RF expressionand the data points in Table 43 are depicted in Figure 47h5The expression wasused to calculate segment-specific recovery factors and estimate the technicallyrecoverable hydrokinetic energy resource throughout the contiguous 48 states

Figure 4-2 Two views of a plot of the Recovery Factor scenario results (data points) listed in Table 43 and fitted Recovery Factor function (surface plot)

4-8

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 38: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

For Alaska data on river slope was not readily available Hence the RecoveryFactor was estimated based on the flow rate alone using

119877119865 = 00557 119897119899(119876) minus 02946 Eq 4-4

The above equation (with an R2 of 078) was obtained from the Recovery Factor and flow rate data from Table 43 The relationship between annual average flowrate and recovery factor is displayed in Figure 43 below

y = 00557ln(x) - 02946 Rsup2 = 07798

0

005

01

015

02

025

03

0 5000 10000 15000 20000 25000

Reco

very

Fac

tor

Annual average flow rate (cubic meters per second)

Figure 4-3 Plot showing the relationship between Recovery Factor and discharge based on data in Table 43

This recovery factor function was applied to the discharge data for individual river segments identified in Appendix C to estimate the technically recoverablein-stream hydrokinetic power for those Alaska river segments with averagedischarge greater than 10000 cfs

4-9

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

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as well as experts from academia and industry to help address

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the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 39: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 5 Results for the Technically Recoverable Hydrokinetic Resource

The technically recoverable resource is presented by hydrologic region in Table51 The total estimated technically recoverable power is 120 TWhyr The Lower Mississippi region contributes nearly half (479) of the total resourceestimate The major rivers of Alaska constitute 171 of the total for thecontinental US The next largest contributor is the Pacific Northwest region which contributes 92 followed by the Ohio region (57) Collectively thesefour regions encompass 80 of the technically recoverable hydrokinetic resourcein the continental US

Table 5-1 Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) ()

New England 02 02

Mid Atlantic 10 08

South Atlantic Gulf 12 10

Great Lakes 001 02

Ohio 69 57

Tennessee 10 09

Sauris Red-Rainy 003 003

Upper Mississippi 51 42

Lower Mississippi 574 479

Texas Gulf 005 004

Arkansas Red 13 10

Lower Missouri 56 47

5-1

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 40: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 5-1 (continued) Technically recoverable hydrokinetic resource for the continental United States by hydrologic region depicted in Figure 31 and for Alaska

Portion of Total Technically Technically

Recoverable Annual Recoverable Resource Hydrologic Region Energy (TWhyr) () Upper Missouri 28 23

Rio Grande 03 02

Lower Colorado 39 32

Upper Colorado 11 09

Great Basin 0 0

California 07 06

Pacific Northwest 110 92

Alaska 205 171

Total 1199

5-2

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

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as well as experts from academia and industry to help address

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Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 41: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource

Uncertainty in the theoretical resource is directly related to uncertainty in thedischarge and in the river slope as is evident in Eq 11 The project team examined uncertainty of the total theoretical resource estimate as well asuncertainty of the theoretical resource estimate in individual river segments Theuncertainty of the overall resource estimate was judged to be relatively small Theteam examined river elevation change between the headwaters and the rivermouth as represented by NHDPlus and as estimated by an alternative source(Table 61) The NHDPlus data was in good agreement with the alternative dataso it was judged that river slope uncertainty would not contribute significantly tooverall uncertainty in the resource estimate at the scale of entire rivers For individual segments however the percent errors can be larger

Table 6-1 Uncertainty analysis of river elevation change between headwaters and mouth

NHDPlus Alternative Source of Percent River elevation change elevation change alternative difference (m) (m) data

Colorado 1714 1734 1 Google Earth

Missouri 1180 1110 6 Google Earth and Wikipedia

Snake 1986 1960 1 Google Earth

Arkansas 1975 2000 1 Google Earth and Wikipedia

Analysis of NHDPlus and USGS discharge data indicated that uncertainty inNHDPlus discharge data would not contribute to significant uncertainty in theoverall theoretical resource estimate Uncertainty in the NHDPlus discharge(referred to as ldquoMAFLOWUrdquo in the database) was studied by comparingNHDPlus discharge estimates (QNHDPlus) and USGS-gage measurements (QUSGS)

6-1

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 42: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

at a representative location in each of the 36 hydrologic regions represented inthe NHDPlus database (Figure 61) The plot of the individual data points(comparing the two estimates) and the linear regression of QNHDPlus and QUSGS

both show that QNHDPlus is an unbiased estimate of discharge in the riversegments ndash assuming that USGS gage data is reasonably accurate Note USGSgage data has an uncertainty of about 10 for a 30 year record (Benson and Carter 1973) Hence for the overall theoretical resource estimate which isessentially the sum of numerous river segment discharge estimates uncertainty inNHDPlus discharge estimates would not contribute to significant uncertainty inthe overall theoretical resource estimate

However our analysis indicates that there is significant uncertainty in ourestimates of the theoretical resource in individual river segments In individual segments both river slope uncertainty and discharge uncertainty contributedsignificantly to theoretical resource uncertainty For example according to NHDPlus documentation (McKay et al 2012) in some instances it wasnecessary for the NHDPlus developers to manually smooth the river slope in order to get rivers to flow in the correct direction There is also significant uncertainty in the NHDPlus discharge in individual river segments For examplein the data shown in Figure 61 the NHDPlus discharge deviated from theUSGS measurement by 77 (on average) with some minor over-estimation of discharge (in the NHDPlus estimate) at low flow rates

Figure 6-1 Comparison of NHDPlus-estimated discharge and USGS gage measured discharge at selected locations in each of the hydrologic regions of the US

6-2

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 43: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

The uncertainty in the estimation of the recovery factor and technical resource can be studied by examining the methodology used to estimate the recoveryfactor As described in )( 4 an expression for the recovery factor as afunction of average discharge and as a function of river slope was developed basedon a ldquocase studiesrdquo approach The case studies assumed a ldquoVrdquo ndash shaped channelprofile with a side slope of 006 and it assumed normalized flow distributioncurve based on flow statistics from the Mississippi River at VicksburgMississippi In order to estimate the uncertainty in the recovery factor (andtechnical hydrokinetic resource) a number of sensitivity studies were done Thesestudies included 1 A comparison of the recovery factor calculated for an idealized V-shaped

channel (side slope = 0021) with that for a real channel with the sameaverage side slope

2 A comparison of the recovery factor calculated for an idealized V-shapedchannel with a side slope of 006 with that calculated for side slopes of 003and 009 (using the case shown in Table 42 as a baseline)

3 A comparison of the recovery factor calculated assuming in-row spacing of2D between devices with a spacing of 1D between devices

4 A comparison of the recovery factor calculated assuming Q5Qave = 018 (Table 41) with the recovery factor calculated assuming Q5Qave = 035

5 A comparison of the recovery factor calculated assuming a Manningroughness coefficient of 0025 instead of 003

A summary table presenting the sensitivity of Recovery Factor to effects 1through 5 above is provided in Table 62 below The sensitivity study indicatesthat the recovery factor for a given river segment is uncertain Since the recoveryfactor and the theoretical resource in a given segment are uncertain to a largedegree it is clear that technical resource in a given segment is also quiteuncertain We can next turn our attention to the uncertainty of the overalltechnical resource estimate Earlier we argued that the estimate of the overalltheoretical resource is fairly certain since there was no significant source of bias inthe theoretical estimates in individual river segments Here we again argue thatthe overall theoretical resource is fairly certain since there are no significantsources of bias in the recovery factor A potential source of bias (on the order of16) is the bias in NHDPlus flow rates relative to USGS gage measurements

6-3

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 44: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table 6-2 Sensitivity of Recovery Factor calculation

Sensitivity Sensitivity test ( change from baseline)

Use real river profiles instead of ldquoVrdquo shape 15

Use of side slope of 03 or 009 instead of 06 -9 9

Device spacing of 1D (not 2D) in rows -4

Q5Qave = 35 instead of 18 16

Manning roughness of 0025 instead of 003 4

More insight into sources of uncertainty in this project is obtained by examiningthe NHDPlus database in more detail Though NHDPlus is the best dataset fora project of this scope it is important to note its limitations Also NHDPlus does not exist for the State of Alaska which requires a different approach A more detailed description of NHDPlus is at httpwwwhorizon-systemscomNHDPlusdataNHDPLUS_UserGuidepdf

The user of these data should be aware that while these data can be used to obtain a useful estimate of the hydrokinetic resource in the contiguous 48 states as well as the broad scale distribution of the resource the data are not suitable for identifying sites suitable for hydrokinetic project deployments

6-4

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 45: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 7 GIS Display The geo-spatial results of this assessment are available as an interactive web-based Geographic Information System (GIS) application called the River Atlasapp The River Atlas is deployed using the National Renewable EnergyLaboratoryrsquos (NRELs) OpenCarto framework OpenCarto is an openarchitecture framework that utilizes open source libraries (eg MapServer TileCache Ext-JS and OpenLayers) and standards such as Styled LayerDescriptor (SLD) Web Mapping Service (WMS) and Web Feature Service(WFS) OpenCarto is designed to support analysis visualization and data exploration and is an ideal medium for the visual representation of the riverinehydrokinetic data Currently results are only available for the 48 contiguousstates Results will be made available for Alaska in the future

Data Processing

NREL received the data as GIS shapefiles along with a MXD file The shapefiles contain the data variables and georeferenced coordinates The MXD file was used as a reference for styling the visual representation of the data withinthe stand-alone application

The shapefiles were re-projected in the WGS_1984 Geographic CoordinateSystem for compatibility with the OpenCarto framework The re-projected datawere then converted from shapefiles to a PostGIS object relational database

OpenCarto can access the data from the spatial database repository and bycreating unique layers for each data variable the hydrokinetic data can berendered in a web mapping application The river networks are displayed as linesegments reflecting the power variable in the database and classed by standarddeviation Unique layers were created for three power classes (low medium and high) By default the layers are generated as simple spatial geometries with noassociated style Applied rules give each power class a line color and stroke width

Tool Functionality and Capabilities

The River Atlas app is a web-based application that was selected as the tool tovisually display the riverine hydrokinetic resource data it is a specific applicationmodule that is hosted on the OpenCarto platform The data are displayed by adding the layers to the application module The river app was assigned a URL (httpmapsnrelgovriver_atlas) to allow users to access and interact with the

7-1

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 46: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

data The basic components of the application are a map window for displayingthe data a content display window (which uses tabs to display the map layers legend and data sources) and a toolbar

The River Atlas app has additional capabilities that allow the user to interact with the data and create customized visualizations and maps The query tool provides several options that return query results from the spatial database The data can be queried by point region or attribute The query will return resultsfrom the geometry feature(s) in a new window and also highlight the selectedfeature(s) on the map Region query results can be downloaded by the user as a CSV file

OpenCarto capabilities allow users to generate their own thematic maps The layer tree can be customized to reorder the layer index class thresholding can beperformed to display only the data of specific interest to the user and legend and class display colors can be customized Data results can be downloaded and customized maps can be printed if desired

Application Analysis

The interactive capabilities of the application can be used for basic data analysison active layers Results for specific user-selected geographic points or regionscan be returned using the query tool The query results can be coupled withother layers to obtain answers to questions such as estimating the resourcepotential in a specific county or state

A combination of capabilities and tools can also be used to determine distancefrom a specified river segment By using layer thresholding a user can displayonly power values within specified numerical bounds Then using the measure tool a distance from those river segments to the nearest point of interest (eg city or known transmission line) can be estimated

The flexibility of the application and customization of the data allows users toperform basic analysis and with the capability of downloading the data users canperform their own advanced analysis and modeling

Intended Audience

The mission of DOEs Water Power Program is to perform and sponsor thenecessary research development testing evaluation and demonstration ofinnovative water power technologies leading to cost-effective environmentallyresponsible generation of renewable energy including from marine and hydrokinetic (MHK) resources

The River Atlas app is a tool that supports attainment of this goal by providingan easy-to-use interactive visual interface This type of interface is beneficial both to audiences who may be familiar with marine and hydrokinetic resourcesand also to those who are exploring them for the first time

7-2

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 47: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

The application can deliver insight and facilitate discovery of geographic regionsand riverine systems with relatively high hydrokinetic resources While the application and supporting data are not suitable for siting studies they may help researchers and others identify rivers meriting more in-depth data collection and siting studies

7-3

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 48: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Section 8 Conclusions An information base exists from which the theoretically available and technicallyrecoverable riverine hydrokinetic resource can be estimated for the continentalUnited States These data were used to make such an assessment utilizingestablished hydraulic engineering principles and advice from relevant expertsThe resulting assessment substantially advances understanding of thehydrokinetic resource potential in the continental United States The more detailed and comprehensive assessment reported here yields an estimate oftechnically recoverable hydrokinetic energy (1199 TWhyr) that is approximately9 greater than the estimate from the only other nationwide assessment (ie Miller et al 1986) A difference of this magnitude is not unexpected given the differences in criteria for waterbody inclusion and differences in analytical methodology Large differences between the two studies in regional distributionof the resource can be attributed to differences in methodology as well

The data gathering and reporting programs supplying the data however werenot designed and implemented with hydrokinetic resource assessment as anintended application of the data Furthermore operating riverine hydrokineticprojects donrsquot yet exist to provide a means of validating important assumptionsincorporated into this assessment Consequently the assessment substantiallyadvances understanding of the hydrokinetic resource potential of the UnitedStates however substantial uncertainty remains Uncertainty and error aregreatest at the scale of individual segments and results are not appropriate for siting projects or ranking river segments Further work is needed to develop andvalidate models of the hydraulic effects of hydrokinetic turbine projects Such modeling tools are needed for refined resource assessment project planning andenvironmental impact assessment

Improved understanding also is needed of the practical constraints on development of the hydrokinetic resource and of the impact of those constraintson the portion of the technically recoverable resource that may ultimately beexploited Significant improvements in understanding of the hydrokineticresource will require more detailed hydrologic information site-specificinformation on constraints imposed by existing uses and environmentalsensitivities and empirical validation and refinement of hydrokinetic arraymodels Given the uncertainties that currently exist the practical resource is anunknown fraction of the technically recoverable resource estimated by this study

8-1

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

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the United States and international participation extends to more than

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Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 49: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Appendix A Validation The National Renewable Energy Laboratoryrsquos validation of the hydrokineticenergy resource values in the GIS database was different from NRELrsquos previousvalidations of wind and wave power estimates Due to the scarcity of completestream-flow and channel cross-section information all available information wasused to help compute the in-stream resource meaning that these data can nolonger serve as an independent data set for validation Moreover we know of nodirect measurements of in-stream energy that could be used to validate themodel

Consequently NRELrsquos validation effort was limited to the inspection of theestimated resource values to verify that they are reasonable consistent over time reproducible and were within the statistical bounds of other naturally varyingriver systems

The primary validation process consisted of a statistical analysis of the individual river segments and their contribution to the total resource Segments weregrouped by power output power per km slope flow and other measures and thelargest values in each group were inspected manually GoogleEarth was used todetermine whether high power values were caused by actual high-gradient regions or by dams that had slipped through the automated dam identificationprocess Segments were also grouped by river and obvious outliers were removedThis power screening process also identified a few segments at the US-Canada border that had erroneous values of delta-h

After removal of all anomalous segments the remaining segments were sorted bypower The top 10 most powerful segments were all located on the Mississippi River Almost two-thirds of the top 150 segments were on the Mississippifollowed by the Colorado Ohio Missouri and Columbia Rivers A final rankingof the top power producing rivers is shown in Table A-1

A-1

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 50: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table A-1 Top Rivers by Power Production

Theoretical Power River (TWhyr)

Mississippi River 2173

Colorado River 792

Missouri River 598

Snake River 417

Ohio River 405

Arkansas River 298

Rio Grande 285

Yellowstone River 264

Columbia River 263

Salmon River 226

The general order shown in this table is roughly what one would expect Thehigh value for the Snake River is due to a few segments with high delta-h but these may be in error Some high powers from the Colorado and YellowstoneRivers are from rapids andor waterfalls These features are often located innational parks or other protected sites and would be removed from considerationif a complete database of environmental exclusions were applied

As riverine hydrokinetic project siting studies and deployments accrue datasuitable for further model refinement and validation will become available

A-2

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

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Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 51: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Appendix B Hydraulic Impacts of Hydrokinetic Devices

Abstract

A simple technique to estimate the far-field hydraulic impacts associated with thedeployment of hydrokinetic devices is introduced The technique involvesrepresenting the presence of hydrokinetic devices as enhanced bottom roughnessThe enhanced Manning roughness is found to be a function of the Manningroughness of the natural channel device efficiency blockage ratio density of device deployment and water depth The technique is developed assumingsimple open channel flow geometry However once the effective bottom roughness is determined it can be used to determine the hydraulic impact ofarbitrary device configurations and arbitrary flow situations

Introduction

Hydrokinetic energy conversion devices are deployed in flowing water and theyextract energy according to the kinetic energy or velocity of the flowing water The power available from hydrokinetic devices per unit swept area is termed thehydrokinetic power density (PD W m-2) Hydrokinetic power density is a function of fluid velocity (V m s-1) fluid density (ρ kg m-3) and device efficiency (ξ)

119875119863 = 120585 120588 1198813 Eq B-1 2

However as hydrokinetic (HK) devices extract power from flowing water theycan alter the flow velocity water elevation sediment transport and other river properties and processes The goal is to develop simple ways of estimating andrepresenting the far-field hydraulic impacts of HK device deployments Inparticular we develop a technique for representing the presence of hydrokineticdevices with an enhanced bottom roughness The enhanced bottom roughnesscan be used in standard hydraulic calculation procedures and models to determinethe device impact

A widely-used open channel flow equation for relating flow velocity (ordischarge) to bottom roughness and channel properties is the Manning Equation Here the equation is presented in two forms

B-1

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

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conducts research and development relating to the generation delivery

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TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 52: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

1 2 3 1 2 A 2 3 1 2V = R S or Q = R S Eq B-2 n n

where V is the cross-section averaged velocity (m s-1) n is the Manning roughness coefficient (m-13 s) R is the hydraulic radius (cross-sectional areawetted perimeterm) S is the slope Q is the discharge (m3 s-1) and A (m2) is the cross-sectional areaNote the second version of the Manning Equation is obtained from the first versionthrough application of the continuity principle (Q =VA) Since HK devices tend toimpede the flow of water they can be represented with an enhanced bottomroughness nt According to the Manning Equation all other parameters beingunchanged an enhanced bottom roughness would cause a reduction in velocity In a river setting where the discharge can be considered constant the reduced velocitywill be compensated for with an increase in water depth The majority of previous work on the interaction of hydrokinetic devices and flowing water focused on the calculation of the available hydrokinetic power intidal systems (Garrett and Cummins 2005 Bryden and Couch 2006 Sutherlandet al 2007 Garrett and Cummins 2008 Karsten et al 2008 Polagye 2009) In tidal systems often conceptualized as a channel connecting two basins ndash one semi-infinite and one finite ndash the central question is what fraction of the totalenergy passing through the tidal channel is available for HK extraction Theresearchers found that as the number of hydrokinetic devices increased the flowrate of water through the channel decreased Further as the number of devicesincreased there was a peak in total energy extraction followed by a decline

Researchers (eg Garrett and Cummins 2007 Garrett and Cummins 2008) havealso addressed the question of the relationship between the power extracted byhydrokinetic devices (Pextraction) and the total power dissipated by the presence of the devices (Pdissipation) The power extracted by hydrokinetic devices is theproduct of the power density (PD) and the swept area of the devices Focusing ona single device in a channel they noted that the devices generated a low velocityzone in their wake Further when the low water velocity wake mixed with thehigh velocity water that flowed around the device significant energy wasdissipated Garrett and Cummins (2007 2008) report

P 2extraction = Eq B-3 P 3(1 + ε )

dissipation

where is the blockage coefficient (ie the fraction of the river cross-sectionalarea occupied by the HK device) In this formulation Pdissipation is the total power dissipated in a stretch of river It is assumed that there are negligible drag losses

Analysis

Here we derive an expression for an enhanced or effective Manning roughnesscoefficient (nt) that can be used to represent the presence of hydrokinetic devicesThe expression is obtained by considering the conservation of energy equation intwo simple flow situations ndash Case A and Case B Case A is a wide open channelflow situation in which the flow is steady and uniform In Case B hydrokineticdevices have been deployed such that they are distributed uniformly throughoutthe channel bottom The channel in Case B is otherwise identical to the one in

B-2

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 53: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Case A An expression for an enhanced Manning roughness that accounts for the presence of devices is readily determined by assuming that the total flow rateis the same in both situations

Representation of hydrokinetic devices with an enhanced bottom roughness

Case A ndash uniform open channel flow with no hydrokinetic devices

Assuming flow from Location 1 to Location 2 the energy conservation equation(or modified Bernoulli Equation) for Case A (no devices) can be written(Munson et al 2002)

2 21198751 1198752

120574 + 1198811 =

120574 + 1198812 Eq B-4

2119892 + 1199111 2119892

+ 1199112 + ℎ119871

where P1 and P2 are the pressures (Pa) at locations 1 and 2 respectively

V1 and V2 are the velocities (m s-1) at locations 1 and 2 respectively z1 and z2 are the elevations (m) at locations 1 and 2 respectively γ is specific weight (N m-3)

g is acceleration due to gravity (98 m s-2) and hL is head loss (m) due to bottom friction

Since flow is uniform in the direction of flow the pressure and velocity termscancel out and the energy equation can be written

1199111 minus 1199112 = ∆119911 = ℎ119871 Eq B-5

Further recognizing that for uniform flow the bottom slope is the ratio of thehead loss to the length of the channel section (ie S = hLL) ManningrsquosEquation (Eq B2) can be rearranged to obtain head loss in terms of the flowrate Manningrsquos roughness channel cross section area (A m2) and hydraulic radius (R m)

119876119899

2

ℎ119871 = ∆119911 = 2 119871 Eq B-6 1198601198773

Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices

In Case B the channel of Case A is altered to include hydrokinetic devices (ie turbines) that are distributed uniformly on the channel bottom Water pressure(P1t and P2t) and flow velocity (V1t and V2t) differ from that seen in Case A due tothe turbine presence However variables such as discharge channel width andbottom slope remain the same The energy conservation equation for Case B hasthe following form

B-3

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 54: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

2 21198751t 1198752t 120574

+ 1198811t = 120574

+ 1198812t Eq B-7 2119892

+ 1199111 2119892 + 1199112 + ℎ119871119905 + ℎ119901

where ℎ119871119905 is the head loss due to the bottom friction (ie contact of the flowingwater with the ldquonaturalrdquo channel bottom) and hp is the ldquohead lossrdquo associated with the presence of the hydrokinetic devices (described below)

Since the turbines are uniformly distributed flow conditions continue to beuniform in the direction of flow Consequently upstream and downstreamvelocity and pressure heads are the same and Equation B7 can be simplified to

1199111 minus 1199112 = ∆119911 = ℎ119871 119905 + ℎ119901 Eq B-8

Using the same approach as for Equation B5 the head loss associated withbottom friction can be expressed

2

= 119876119899 ℎ119871 119905 2 119871 Eq B-9 1198601199051198771199053

where At and Rt are the cross-sectional area and hydraulic radius of the channel when turbines are present Since the channel geometry in the two cases is the same Equation B8 can be written using Equations B7 and B9 obtaining

2

119876119899

2

119871 = 119876119899

2 2 119871 + ℎ119901 Eq B-10 119860119877 3 1198601199051198771199053

Assuming a very wide rectangular channel such that the hydraulic radius is thewater depth and the cross-sectional area is the product of the width and depth Equation B10 becomes

2

119876119899

2

119871 = 119876119899

5 5 119871 + ℎ119901 Eq B-11 119908ℎ 3 119908ℎ1199053

where ht is the water depth with devices present

Channel energy losses due to presence of hydrokinetic devices

Assuming drag losses to be negligible (following Polagye (2009)) the total power dissipated can be estimated based on the blockage area and extracted power asdescribed in Equation B3 The total power dissipation can be expressed as a ldquohead lossrdquo (ie as hp) by dividing by the product of discharge and the specific weight (ie γ Q) obtaining

Pdissipation 3 120588119873119860119903Vt3 3 1198731198601199031198762 1ℎ119901 = = (120585 (1 + ϵ)) = ∙ 120585 (1 + ϵ) ∙ 3γQ 4 γ Q 4 1198921199083 ℎ119905

Eq B-12

B-4

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 55: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

where N is the number of hydrokinetic devices in the channel segment

Ar is the swept area of an individual hydrokinetic device (m2)

Vt is the cross-section averaged velocity with devices present (m s-1)

w is the channel width (m) and

ht is the channel depth with devices present (m2)

Determination of water depth with devices present

Using the expression for ldquohead lossrdquo due to the presence of hydrokinetic devices(Equation B12) Equation B11 can be rearranged obtaining

120585(1+ϵ) 119873119860119903 minus3 ℎminus103 minus ℎ119905minus103 minus 3 ∙ ∙ ℎ119905 = 0 Eq B-13

4 1198992119892 119908119871

From Equation B13 it is apparent that the increased depth associated with thedeployment of hydrokinetic devices (ht) can be determined from the character ofthe channel and the character and number of the devices Through the principleof continuity the cross-section averaged velocity can also be determinedEquation B13 was rearranged obtaining

1199093 minus 119909minus13 minus 119886 = 0 Eq B-14

120585 (1+ϵ) 119873119860119903where x = ℎℎ119905 and a = 3 ∙ ∙ ℎ13

4 1198992119892 119908119871

Next Equation B14 was approximated by a cubic polynomial (usingMATLAB)

10849 ∙ 1199093 minus 045336 ∙ 1199092 + 098303 ∙ 119909 minus 16145 minus a = 0 Eq B-15

The cubic polynomial was solved (for x) and the solution was used to determinethe following relationship between ht h and a

ℎ119905 = ℎ middot 11988713 minus 028263 middot 119887minus13 + 0139296 Eq B-16

119908ℎ119890119903119890

119887 = 046088 middot 119886 + ((046088 middot 119886 + 068368)2 + 0022578)12 + 068368

For values of x ranging from 1 to 15 and for a ranging from 0 to 250142 thecubic polynomial approximation was found to generate estimates of x ( or ℎ119905) that

ℎwere very accurate (within 10-3 percent) Equation B16 demonstrates that thehydraulic impacts of a uniform distribution of hydrokinetic devices can beestimated based on a single parameter (parameter a Eq B14)

B-5

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 56: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Determination of the effective Manningrsquos roughness coefficient and velocity with devices present

Having determined hth as a function of parameter a the enhanced Manningroughness coefficient representing the presence of the hydrokinetic devices (ie turbines) can be readily determined Since the discharge and slope under Case A and B are the same the Manning Equation (Equation 2) can be used to establisha relationship between h ht n and nt

2

(ℎ119905)2119908ℎ 119908ℎ119905ℎ3 = 3 Eq B-17

119899 119899119905

Solving for nt we have

53 = ℎ119905119899119905 ℎ

∙ 119899 Eq B-18

Based on the continuity principle the velocity with devices present (Vt m s-1) can also be determined based on hth or ntn

119881119905 = ℎ V =

119899 35 V Eq B-19

ℎ119905 119899119905

Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices

In order to illustrate the technique for estimating the hydraulic impact ofhydrokinetic devices a set of channel flow and hydrokinetic device propertieswere assumed (Table B1) Further it was assumed that the hydrokinetic deviceswere deployed in rows (normal to the flow) separated by 10 device diameters (ie 10 D or 80 m) Given the properties in Table B1 it is clear that we weremodeling a single row of devices with the roughness of the devices distributedthroughout the channel length Then assuming an increasing number of devicesper row (or number of devices in the 80 m long channel segment) the impact ofthe devices on the normalized depth (hth) normalized effective bottom roughness (ntn) and normalized velocity (VtV) were calculated based onEquations B16 B18 and B19 respectively as a function of the number ofdevices per row (or per 10 D of channel length) (Figure B1) In this example the maximum number of devices per row was capped at 20 This amounts tospacing between devices of 179 m or 22 D This spacing is approximately equal to 2D which is often considered an upper density limit

B-6

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 57: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table B-1 Channel flow and turbine properties assumed in example calculation

Variable Symbol Value water depth h 10 m

channel width w 500 m

channel length L 80 m

Slope S 00002

Manning roughness n 0025

turbine efficiency ξ 32

turbine swept area Ar 51 m2

Figure B1 also shows the blockage ratio (ϵ) power density and total power (for a 80 m long channel) as a function of density of hydrokinetic devices (ienumber of devices per row) It is noteworthy that the normalized depth Manning roughness and velocity all start at a value of 10 on the left side of theplot (where the device density is 0) As the density of devices increases thenormalized depth and Manning roughness monotonically increase whereas thenormalized velocity decreases Initially the total extracted power increasesrapidly Later there are diminishing returns in extracted power with incrementalincreases of device density This is because the water has been slowed by the devices that have already been deployed in the channel The diminishing energy level of the channel with increasing device density is shown by the power densitycurve which decreases rapidly with increasing numbers of devices

0

100

200

300

400

500

600

700

800

900

00

05

10

15

20

25

30

0 5 10 15 20

P [k

W]

Dim

ensi

onle

ss s

cale

amp P

D [k

Wm

2 ]

N [ of turbines per row assuming rows separated by 10middotD]

Figure B-1 Plot of normalized depth (hth ) normalized velocity (VtV ) normalized effective Manning roughness (ntn ) power density (PD kW m-2 ) extracted power in a 500-m long channel section (P kW ) and blockage ratio ( )as a function of density of hydrokinetic devices (number of devices per 10 D m length)

B-7

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 58: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

The blockage ratio plotted in Figure B1 and used in equation B14 is based onthe water depth in a device-free channel (h) That is the calculations of blockageratio presented here do not account for the depth increase due to the presence ofHK devices Calculations show that including these ldquoback effectsrdquo in the blockageratio has a negligible effect on water level For example for the situation shownin Figure B1 if the back effect is accounted for the hth ratio at 20 devices per row would decrease from 1506 to 1486 change5) 5g8iz

Hydraulic impacts of HK devices associated with deployments in spatially limited areas

The previous section indicated that a uniform distribution of hydrokineticdevices can have a significant impact on water level and velocity In order todetermine the impact of hydrokinetic devices when they are deployed in limitedareas a 1D numerical model (ISIS) was employed To illustrate the impact ofdifferent spatial extents of hydrokinetic device deployments a single device density (27 devices per 500 m segment or 45 per 80 m segment) and the same channel geometry was assumed (Table B2) However the longitudinal extent ofthe deployment was limited to just 500 m (Figure B2) In this case the water level and velocity impact was significantly reduced relative to the impactsobtained if the device deployment was unlimited in the longitudinal direction(Figure B3) Specifically the enhancement in water level was only about 6 cminstead of about 11 m

Table B-2 Channel flow and turbine properties assumed

Variable Symbol Value

water depth h 10 m

channel width w 500 m

Slope S 00002

Manning roughness (no devices) n 0025

turbine efficiency 120585 32

turbine swept area Ar 51 m2

Manning roughness (18 devices per 100 m Segment)

nt 00308

B-8

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 59: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Figure B-2 Cartoon illustrating the spatially limited deployment of hydrokinetic devices

B-9

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 60: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

2597

2607

10 1005

101 1015

25 50 75 100 125 150 175

velo

city

ms

dept

h m

Distance km

h V(a)

2598 2601 2603 2606 2608 2611 2613 2616

10040

10060

10080

10100

995 100 1005 101 ve

loci

ty m

s

dept

h m

Distance km

h V(b)

099

0995

1

1005

101

0 50 100 150

Distance km

VtV hth (c)

Figure B-3 Hydraulic impact of a spatially-limited deployment of hydrokinetic devices including (a) velocity and water depth within 75 km of the hydrokinetic devices (b) Velocity and water depth within 05 km of the devices and (c) normalized velocity and normalized depth proximal to the devices

B-10

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 61: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

L

Notation

119860 cross sectional area of the channel (m2)

119860 119905 cross sectional area of the channel for the case when turbines are uniformly distributed over the bottom (m2)

119860119903 cross sectional area of the rotor for one turbine unit (m2)

119862119889 drag coefficient

119865119889 drag force (N)

119892 acceleration due to gravity (981 ms2)

ℎ water depth (m)

ℎ119864 head loss due to due to power extraction (m)

ℎ119865119863 head loss due to due to the drag force for one turbine unit (m)

ℎ119871 119905 head loss due to bottom fiction the case when turbines are uniformly distributed over the bottom (m)

ℎ119871 head loss due to bottom fiction (m)

ℎ119901 head loss due to turbines operation caused by power production and drag forces acting on the turbines (m)

ℎ119905 water depth for the case when turbines are uniformlydistributed over the bottom (m)

channel length (m)

mass flow rate (kgs)

119899 Manningrsquos roughness coefficient

119899119905 effective Manningrsquos roughness coefficient that is attributed to placing turbines

11987512 pressure at the point (Nm2)

ρ fluid density (1000 kgm3 )

119876 volume flow rate (m3s)

119877 hydraulic radius (m)

B-11

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 62: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

119877 119905 hydraulic radius for case when turbines are uniformlydistributed over the bottom (m)

119878 slope of the channel (mm)

119880119899 velocity ratio (or tip speed ratio)

119881 average fluid flow velocity in the channel (ms)

11988112 fluid flow velocity at a point on a streamline (ms)

power (Watts)

119908 channel width (m)

11991112 elevation of the point above a reference plane (m)

∆119911 elevation change over the channel length (m)

120574 specific weight (Nm3)

120585 turbine efficiency

ε blockage ratio

120590 turbine solidity

B-12

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 63: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska

The theoretical resource was estimated for the segments of major Alaska riverswith average discharge greater than 10000 cfs These river segments and their associated theoretical power are listed in Table C-1

C-1

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 64: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table C-1 Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Yukon Kaltag Pilot Station 6284 302 18588 163

Ruby Kaltag 5413 131 6954 61

Stevens Village Ruby 4031 479 18910 166

Eagle Stevens Village 2876 1683 47439 416

TOTAL 805

Koyukuk Hughes Koyukuk 575 500 2819 25

66 34rsquo N 152 38rsquo W Hughes 408 308 1231 11

66 49rsquo N 151 47rsquo W 66 34rsquo N 152 38rsquo W 282 439 1213 11

TOTAL 46

Tanana Fairbanks Nenana 621 284 1724 15

Big Delta Fairbanks 485 1637 7775 68

Tok Junction Big Delta 300 4524 13319 117

TOTAL 200

Kuskokwim Chuathbaluk Bethel 1773 268 4662 41

Crooked Creek Chuathbaluk 1415 143 1987 17

Stony River Crooked Creek 1120 198 2175 19

62 23rsquo N 156 0rsquo W Stony River 854 232 1938 17

6247rsquo N 155 45rsquo W 62 23rsquo N 156 0rsquo W 632 149 925 08

63 0rsquo N 154 54rsquo W 6247rsquo N 155 45rsquo W 446 79 347 03

TOTAL 105

C-2

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 65: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Stikine 56 40rsquo N 132 7rsquo W Coast 3863 08 312 03

56 42rsquo N 132 0rsquo W 56 40rsquo N 132 7rsquo W 3843 25 930 08

56 93rsquo N 131 51rsquo W 56 42rsquo N 132 0rsquo W 3816 37 1391 12

TOTAL 23

Kvichak 59 12rsquo N 156 26rsquo W Coast 738 101 728 06

59 15rsquo N 156 5rsquo W 59 12rsquo N 156 26rsquo W 723 37 259 02

59 20rsquo N 155 54rsquo W 59 15rsquo N 156 5rsquo W 699 16 106 01

TOTAL 09

Nushagak 58 52rsquo N 157 50rsquo W Coast 827 31 250 02

59 2rsquo N 157 46rsquo W 58 52rsquo N 157 50rsquo W 823 55 445 04

59 18rsquo N 157 34rsquo W 59 2rsquo N 157 46rsquo W 772 69 525 05

59 25rsquo N 157 19rsquo W 59 18rsquo N 157 34rsquo W 714 145 1012 09

59 32rsquo N 157 5rsquo W 59 25rsquo N 157 19rsquo W 696 98 669 06

59 48rsquo N156 48rsquo W 59 37rsquo N 15 76rsquo W 296 330 959 08

TOTAL 34

Susitna Sunshine Cook Inlet 862 777 6570 58

62 17rsquo N 150 8rsquo W Sunshine 555 168 912 08

62 24 150 10rsquo W 62 17 150 8rsquo W 343 131 441 04

TOTAL 69

C-3

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 66: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Porcupine 67 25rsquo N 141 1rsquo N 66 35rsquo N 145 21rsquo N 454 832 3704 32

TOTAL 32

Colville 69 54rsquo N 151 29rsquo W Coast 319 149 467 04

Umiat 69 54rsquo N 151 29rsquo W 295 695 2009 18

65 9rsquo N 154 24rsquo W Umiat 218 1055 2250 20

TOTAL 41

Noatak 67 8rsquo N 162 36rsquo W Coast 312 40 122 01

67 17rsquo N 162 40rsquo W 67 8rsquo N 162 36rsquo W 306 08 23 00

TOTAL 01

Copper 60 43rsquo N 144 39rsquo W Coast 1666 381 6223 55

60 49rsquo N 144 31rsquo W 60 43rsquo N 144 39rsquo W 1574 149 2305 20

61 1rsquo N 144 48rsquo W 60 49rsquo N 144 31rsquo W 1462 201 2884 25

61 15rsquo N 144 53rsquo W 61 1rsquo N 144 48rsquo W 1380 110 1484 13

61 25rsquo N 144 39rsquo W 61 15rsquo N 144 53rsquo W 1313 229 2943 26

61 28rsquoN 144 26rsquo W 61 25rsquo N 144 39rsquo W 1306 299 3825 34

61 31rsquo N 144 21rsquo W 61 28rsquoN 144 26rsquo W 822 95 761 07

61 31rsquo N 144 18rsquo W 61 31rsquo N 144 21rsquo W 818 58 464 04

61 27rsquo N 144 9rsquo W 61 31rsquo N 144 18rsquo W 806 159 1253 11

61 23rsquo N 144 5rsquo W 61 27rsquo N 144 9rsquo W 798 149 1168 10

61 20rsquo N 143 25rsquo W 61 23rsquo N 144 5rsquo W 778 610 4648 41

61 11rsquo N 142 48rsquo W 61 20rsquo N 143 25rsquo W 707 841 5831 51

C-4

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 67: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Table C-1 (continued) Theoretical in-stream hydrokinetic power in segments of the major Alaska rivers in which the annual average flow rate exceeds 10000 cfs (283 m3s)

River Segment start Segment end Qave

(m3s) ∆H (m)

Power (MW)

Power (TWhyr)

Copper 61 4rsquo N 142 50rsquo W 61 11rsquo N 142 52rsquo W 303 378 1123 10

61 0rsquo N 142 43rsquo W 61 4rsquo N 142 50rsquo W 302 323 956 08

60 57rsquo N 142 40rsquo W 61 0rsquo N 142 43rsquo W 300 128 377 03

61 38rsquo N 144 35rsquo W 61 30rsquo N 144 24rsquo W 521 220 1122 10

61 41rsquo N 144 40rsquo W 61 38rsquo N 144 35rsquo W 490 229 1099 10

61 44rsquo N 144 48rsquo W 61 41rsquo N 144 40rsquo W 465 162 737 06

61 50rsquo N 145 10rsquo W 61 44rsquo N 144 48rsquo W 453 607 2691 24

61 56rsquo N 145 20rsquo W 61 50rsquo N 145 10rsquo W 446 232 1014 09

62 3rsquo N 145 21rsquo W 61 56rsquo N 145 20rsquo W 421 341 1408 12

62 8rsquo N 145 26rsquo W 62 3rsquo N 145 21rsquo W 344 247 833 07

TOTAL 396

C-5

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 68: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

The technically recoverable hydrokinetic resource for the selected Alaska river segments with average discharge greater than 10000 cfs is presented in TableC-2

Table C-2 Technically recoverable hydrokinetic resource (TWhyr) in portions of selected Alaska rivers with average discharge greater than 10000 cfs

River Technically Recoverable

Resource (TWhyr)

Yukon 132

Koyukuk 02

Tanana 07

Kuskokwim 11

Stikine 04

Kvichak 01

Nushagak 02

Susitna 05

Porcupine 01

Colville 01

Noatak 0003

Copper 33

Total 199

In )( 3 the theoretical resource in Alaska was estimated to 59 TWhyr inrivers with annual flow rates between 10000 and 1000 cfs Examination of the dependence of recovery factor on discharge (Eq 44) indicates that there wouldonly be a positive recovery factor for flows greater than 7000 cfs In order to obtain an upper bound on an estimate of the technically recoverable resource inAlaska for flows between 10000 and 1000 cfs we calculated the recovery factor (RF) based on a flow rate of 8500 cfs (mid-point between 7000 and 10000 cfs)finding RF = 0011 The Alaska technically recoverable resource for flowsbetween 10000 and 1000 cfs was then estimated to be 06 TWhyr for these lowflow rivers This brought the total technically recoverable in-stream hydrokineticpower in Alaska to 205 TWhyr

C-6

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 69: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Appendix D References Atwater J and G Lawrence 2010 Power potential of a split channel REnewable Energy 35 329-332

Benson M A and R W Carter 1973 A National Study of the Streamflow Data-Collection Program US Geological Survey Water-Supply Paper 2028

Blanchfield J C Garrett P Wild and A Rowe 2008 The extractable power from a channel linking a bay to the open ocean Proceedings of the Institution ofMechanical Engineers Part A Journal of Power and Energy 222(3) 289-297

Bryden I and S J Couch 2006 ME1 -- marine energy extraction tidalresource analysis Renewable Energy 31(2) 133-139

Couch S J and I G Bryden 2004 The impact of energy extraction on tidalflow development 3rd IMarEST International Conference on Marine Renewable Energy 2004

Defne Z K A Haas and H M Fritz 2011 GIS based multi-criteriaassessment of tidal stream power potential A case study for Georgia USA Renewable and Sustainable Energy Reviews 15(5) 2310-2321

EPRI (Electric Power Research Institute) 2006 Methodology for EstimatingTidal Current Energy Resources and Power Production by Tidal In-Stream EnergyConversion (TISEC) Devices Palo Alto CA EPRI-TP-001-NA (Revision 3) September 29 2006

EPRI (Electric Power Research Institute) 2008 System Level DesignPerformance Cost and Economic Assessment -- Alaska River In-Stream Power Plants Palo Alto CA EPRI-RP-006-Alaska October 31 2008

Garrett C and P Cummins 2005 The power potential of tidal currents inchannels Proceedings of the Royal Society A 461 2563-2572

Garrett C and P Cummins 2007 The efficiency of a turbine in a tidal channelJournal of Fluid Mechanics 588 243-251

Garrett C and P Cummins 2008 Limits to tidal current power Renewable Energy 33(11) 2485-2490

D-1

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 70: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Karsten R H J M McMillan M J Lickley and R D Haynes 2008 Assessment of tidal current energy in the Minas Passage Bay of Fundy Proceedings of the Institution of Mechanical Engineers Part A Journal of Power andEnergy 222(5) 493-507

Kartezhnikova M and T M Ravens in review Hydraulic impacts ofhydrokinetic devices Journal of Hydraulic Engineering

Lunden L S and A S Bahaj 2007 Tidal energy resource assessment for tidalstream generators Journal of Power and Energy 221(2) 137-146

McKay L T R Bondelid A Rea C Johnston R Moore and T Dewald 2012 NHDPlus Verson 2 User Guide Prepared for US EnvironmentalProtection Agency Office of Water August 10 2012

Miller G J Franceschi W Lese and J Rico 1986 The Allocation of Kinetic Hydro Energy Conversion SYSTEMS(KHECS) in USA Drainage Basins RegionalResource and Potential Power NYUDAS 86-151 August 1986

Munson B R D F Young and T H Okiishi 2002 Fundamentals of fluid mechanics Wiley New York

NRC-CHC (National Research Council of Canada - Canadian HydraulicCentre) 2010 Assessment of Canadas Hydrokinetic Power Potential Phase I Report Methodology and Data Review

Ortgega-Achury S L W H McAnally T E Davis and J L Martin 2010 Hydrokinetic Power Review Prepared for US Army Corps of EngineersResearch and Development Center Vicksburg Mississippi

Polagye B P C Malte M Kawase and D Durran 2008 Effect of large-scalekinetic power extraction on time-dependent estuaries Journal of Power and Energy 222(5) 471-484

Polagye B 2009 Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Doctoral dissertation University of Washington Seattle WA

Ravens T M M Johnson and M Kartezhnikova in preparation Comparisonof methods for estimating hydraulic impacts of hydrokinetic devices

Shapiro G 2010 Effect of tidal stream power generation on the region-wide circulation in a shallow sea Ocean Science Discussions 7 1785-1810

Sun X J P Chick and I Bryden 2008 Laboratory-Scale Simulation of EnergyExtraction from Tidal Currents Renewable Energy 33(6) 1267-1274

Sutherland G M Foreman and C Garrett 2007 Tidal current energyassessment for Johnstone Strait Vancouver Island Journal of Power and Energy 221 (2)

D-2

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 71: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

Walkington I and R Burrows 2009 Modelling tidal stream power potential Applied Ocean Research 31 239-245

Yang Z and T Wang 2011 Assessment of Energy Removal Impacts on PhysicalSystems Development of MHK Module and Analysis of Effects on Hydrodynamics US Department of Energy Pacific Northwest National Laboratory September 2011

D-3

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References
Page 72: Assessment and Mapping of the Riverine Hydrokinetic ...water.energy.gov/pdfs/riverine_hydrokinetic...Brooke White of the U.S. Department of Energy for their interest in and contributions

The Electric Power Research Institute Inc (EPRI wwwepricom)

conducts research and development relating to the generation delivery

and use of electricity for the benefit of the public An independent

nonprofit organization EPRI brings together its scientists and engineers

as well as experts from academia and industry to help address

challenges in electricity including reliability efficiency health safety and

the environment EPRI also provides technology policy and economic

analyses to drive long-range research and development planning and

supports research in emerging technologies EPRIrsquos members represent

approximately 90 percent of the electricity generated and delivered in

the United States and international participation extends to more than

30 countries EPRIrsquos principal offices and laboratories are located in

Palo Alto Calif Charlotte NC Knoxville Tenn and Lenox Mass

TogetherShaping the Future of Electricity

Program

Environment

copy 2012 Electric Power Research Institute (EPRI) Inc All rights reserved Electric Power Research Institute EPRI and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute Inc

1026880

Electric Power Research Institute 3420 Hillview Avenue Palo Alto California 94304-1338 bull PO Box 10412 Palo Alto California 94303-0813 USA

8003133774 bull 6508552121 bull askepriepricom bull wwwepricom

  • Section 1 Introduction and Background
    • Definition of the Theoretical and Technical In-Stream Hydrokinetic Resource
      • Section 2 Methodology for Estimating the Theoretically Available In-stream Hydrokinetic Resource
        • Contiguous 48 States
        • Preparing the Data
        • Alaska
          • Section 3 Results for Theoretically Available Hydrokinetic Resource
          • Section 4 Methodology for Estimating the Technically Recoverable In-Stream Hydrokinetic Resource
          • Section 5 Results for the Technically Recoverable Hydrokinetic Resource
          • Section 6 Uncertainty of the estimates of the Theoretical and Technically Recoverable Hydrokinetic Resource
          • Section 7 GIS Display
            • Data Processing
            • Tool Functionality and Capabilities
            • Application Analysis
            • Intended Audience
              • Section 8 Conclusions
              • Appendix A Validation
              • Appendix B Hydraulic Impacts of Hydrokinetic Devices
                • Abstract
                • Introduction
                  • Representation of hydrokinetic devices with an enhanced bottom roughness
                    • Case A ndash uniform open channel flow with no hydrokinetic devices
                    • Case B ndash uniform open channel flow with uniform distribution of hydrokinetic devices
                      • Channel energy losses due to presence of hydrokinetic devices
                      • Determination of water depth with devices present
                      • Determination of the effective Manningrsquos roughness coefficient and velocity with devices present
                      • Example calculation of the hydraulic impact of a uniform distribution of hydrokinetic devices
                      • Hydraulic impacts of HK devices associated with deployments in spatially limited areas
                        • Notation
                          • Appendix C Theoretical and Technically Recoverable Riverine Hydrokinetic Power in Alaska
                          • Appendix D References