tidal in-stream energy overview

1LABORATORY FOR ENERGY AND ENVIRONMENTAL COMBUSTION http://www.energy.washington.edu

Tidal In-Stream Energy Overview

Brian PolagyeResearch Assistant

University of WashingtonDepartment of Mechanical Engineering

March 6, 2007


Agenda

• Tidal Energy Status

• TISEC Device Overview

• TISEC in Puget Sound

• UW Research


Past development of the tidal resource has involved barrages

StatusStatusBarrages- Past Development -

001,09-18-06,AR.ppt

250MW barrage in La Rance, France(constructed 1960)

• Dam constructed across estuary requiring long construction time and large financial commitment

• Power produced by impounding tidal waters behind dam

• Drastically alters circulation of estuary in addition to attendant problems with conventional hydroelectric

• Low-cost power production at very large scale


Present development interest is focused on free-stream turbines

StatusStatusTidal In-Stream Energy Conversion (TISEC)- Present Development -

002,09-18-06,AR.ppt

1.5 MW TISEC Device(Marine Current Turbines)

• Turbines installed in groups allowing for more rapid, phased build-out

• Power produced directly from tidal currents

• Should be possible to generate power from tides with limited environmental impact

• Moderate-cost power production at varying scales


TISEC looks like the wind industry about twenty years ago

StatusStatusState of the Industry- Device Developers -

003,09-18-06,AR.ppt

• More than a dozen device developers― Dominant design has yet to emerge― Most developers are UK based due to significant government

investment in marine renewables

• Many developers have tested small-scale models― Laboratory and field tests to verify expected performance― Difficult to address “big picture” questions in the lab

• Full-scale testing just beginning― 300 kW turbine in water in Devon, UK for three years (MCT)― 1.5 MW turbine planned for Strangford, UK in 2006/2007

(MCT)― 6 x 34kW turbine array permitted for East River, NY in 2007

(Verdant)― kW scale ducted turbine at Race Rocks, BC (Clean Current)― OpenHydro testing at EMEC (European Marine Energy

Center) since December 2006


Significant interest in developing this resource in Pacific Northwest

StatusStatusState of the Industry- Pacific NW Activities -

004,09-18-06,AR.ppt

• Many applications have been filed for preliminary permits from the FERC (Federal Energy Regulatory Commission)

― Permit gives applicant three years to study site and precedence for application of full permit― Applications from utilities (municipal utilities given precedence) and site developers― Permit is needed to hook device up to grid, but does not authorize construction and installation.

Subject to the same permitting requirement as any marine construction project.

• A number of studies have been recently carried out, most notably, the ERPI North American Feasibility Study

― 8 prospective sites in US and Canada. For Washington, considered Tacoma Narrows― EPRI also recently produced a report on the in-stream resource in southeast Alaska

• The FERC has recently awarded a number of preliminary permits in Puget Sound― Tacoma Power: Tacoma Narrows (awarded early 2006)― Snohomish PUD: Deception Pass, Agate Pass, Rich Passage, San Juan Channel, Spieden

Channel, Guemes Channel (awarded February 2007)― Competing applications for development in Admiralty Inlet still pending decision


Agenda




• UW Research


All turbines have a number of common components, but many variants

TISEC DevicesTISEC DevicesTurbine Overview

009,09-07-06,SNOPUD.ppt

Rotor• Extracts power from flow• Turns at low RPM• Efficiency varies with flow

velocity (45% max)

Gearbox• Increase rotational speed of shaft

from turbine• 80-95% efficient

Foundation• Secure turbine to seabed• Resist drag on support structure

and thrust on rotor

Generator and Power Conditioning

• Generate electricity• Condition electricity for

grid interconnection• Turns at high RPM• 95-98% efficient

Powertrain or Drivetrain


Foundation selection is usually driven by site water depth

TISEC DevicesTISEC DevicesFoundation Types

010,09-07-06,SNOPUD.ppt

Monopile

• Small footprint• Established technology used

in offshore wind

Gravity Base

Chain Anchors Tension Leg

Hollow steel pile driven or drilled into seabed

Pros:

• High cost in deep water• Installation expensive for

some types of seabed

Cons:

Heavy foundation of concrete and low cost aggregate placed on seabed

• Deep water installation feasible

Pros:

• Large footprint• Scour problems for some

types of seabed• Decommissioning problems

Cons:

• Small footprint• Deep water installation

feasible

Chains anchored to seabed and turbine

Pros:

• Problematic in practice• Device must have high

natural buoyancy

Cons:

Submerged platform held in place by anchored cables under high tension

• Small footprint• Deep water installation

feasible

Pros:

• Immature technology now being considered for offshore wind in deep water

Cons:

(10-40m)


Ducted turbines have been proposed to augment power production

TISEC DevicesTISEC DevicesPower Augmentation

012,09-07-06,SNOPUD.ppt

• Enclosing turbine in diffuser duct may boost power but a number of questions remain unanswered regarding this approach

• Is it economically justified?―Ducts were never justified for wind turbines

―Different set of circumstances for tidal turbines

• Is there an increased hazard to marine mammals and fish?

―Can a large fish or mammal become trapped in the duct?

―Is screening of ducts feasible?


Marine Current Turbines is furthest along in the development process

TISEC DevicesTISEC DevicesMarine Current Turbines (MCT)

002,09-07-06,SNOPUD.ppt

Power trainPower train

FoundationFoundation

MaintenanceMaintenance

DevelopmentDevelopmentLarge Scale

(18 m diameter)Large Scale

(18 m diameter)

Horizontal axis (2 bladed)Planetary gearboxInduction generatorRated from 1.2 – 2.5 MW

Monopile drilled or driven into seabedTwo turbines per pile

Lifting mechanism pulls turbine out of water for servicing

3 years of testing prototype in UK1.5 MW demonstration planned for

installation in 2006/2007Conceptual fully submerged units


Verdant is positioned to install the first array of TISEC devices in the world

TISEC DevicesTISEC DevicesVerdant

002,09-07-06,SNOPUD.ppt




DevelopmentDevelopment

Monopile drilled or driven into seabed

Retrieval of power train by crane bargeDivers employed during installation

Small Scale (5 m diameter)Small Scale (5 m diameter)

Horizontal axis (3 bladed)Planetary gearboxInduction generatorRated at 34 kW

Installing 6 turbines off Roosevelt Island, NY City

First turbine in water producing power


Lunar Energy has adopted a different philosophy with an emphasis on a “bulletproof” design

TISEC DevicesTISEC DevicesLunar Energy

001,09-07-06,SNOPUD.ppt





Large Scale (21 m diameter inlet)

Large Scale (21 m diameter inlet)

Horizontal axis (ducted)Hydraulic gearboxInduction generatorRated at 2 MW

Gravity foundation using concrete and aggregate

Heavy-lift crane barge recovers “cassette” with all moving parts

Tank testingNearing end of design for first large

scale unit


GCK is developing a vertical-axis turbine

TISEC DevicesTISEC DevicesGCK (Gorlov Helical Turbine)

005,09-18-06,SNOPUD.ppt





Vertical axis (3 bladed)Power train TBDRated at 7 kW

TBD – neutral buoyant platform proposed for arrays, bottom mount for single units

TBD – divers?

Testing of single or multiple devices from fixed platforms

Power take-off has been problematic

Small Scale (1 m diameter)Small Scale (1 m diameter)


Agenda




• UW Research


A number of prospective tidal energy sites have been identified in Puget Sound

Puget SoundPuget Sound

006,09-18-06,SNOPUD.ppt

Spieden Channel

San Juan Channel

Deception Pass

Bush Point

Agate Passage

Rich Passage

Guemes Channel

Tacoma Narrows

Marrowstone Point

Point Wilson

700+ MW of tidal resources identified

Large resource Strong currents

Small resource Weaker currents

Puget Sound Site Identification


Case 1: Deception Pass: Exceptional resource quality, small cross-section

021,09-07-06,SNOPUD.ppt

Deception Pass NarrowsSitingSiting

High Power Region

High Power Region Feasible Array LayoutFeasible Array Layout

Preliminary Array Performance


• 20 turbines (10 m diameter)

• Average installation depth ~30m

• Exceptionally strong currents may complicate installation and surveys

• 3 MW average electric power

• 11 MW rated electric power

• Power for 2000 homes

2 km

1 km


Case 2: Admiralty Inlet: Moderate resource quality, large cross-section

022,09-07-06,SNOPUD.ppt

Admiralty InletSitingSiting

Feasible Array LayoutFeasible Array Layout



• 450 turbines (20 m diameter)


• Given lower power density can installation be economic?



• Power for 15,000 homes

Key Next StepKey Next Step

• Velocity survey of Admiralty Inlet to refine power estimates

3 km

0.9 km


Case 3: Tacoma Narrows: High resource quality, moderate cross section

007,09-18-06,AR.ppt

Tacoma NarrowsSitingSiting

BathymetryBathymetry

Study Array PerformanceStudy Array Performance

• 64 turbines (2x18 m diameter)




• Power for 11,000 homes

Point Evans Ref.Point Evans Ref.

Dual Rotor Turbine Footprint

Dual Rotor Turbine Footprint

Study Array LayoutStudy Array Layout


001,3-6-07,UW.ppt

The question of where to site turbines is a relatively complex one

SitingSitingSiting Decision Tree

Is there an in-stream resource?

Is there an in-stream resource?

No

Yes

<10m

No

>60m

Moderate Depth

How deep is the water?

How deep is the water?

Can seabed support

foundation?

Can seabed support

foundation?

No

Yes

Large-scale turbulence?Large-scale turbulence?

No

Marine traffic in area?

Marine traffic in area?

Yes Most/All

Limited

How much of channel occupied?

How much of channel occupied?

NoYes

Is there a low-cost interconnection

point?

Is there a low-cost interconnection

point?

Are there marine construction

facilities?

Are there marine construction

facilities?

No

Yes

Are there other stakeholders?

Are there other stakeholders?

Yes

No

Yes

No

Potential for multiple use?Potential for multiple use?

Yes

OK to BuildOK to Build

Environmental considerations?


015,1-22-07,UW.ppt

Environmental issues usually dominate the discussion and the key questions may be harder to identify, much less answer

SitingSitingEnvironmental Issues

Death of or injury to fish and marine mammals

Death of or injury to fish and marine mammals

Local environmental

degradation

Local environmental

degradation

• Toxicity of anti-fouling paints and lubricants?

• Does turbine operation cause acoustic harassment?

• How will turbine operation and installation affect salmon recovery?

• Will a turbine make sushi in addition to electricity?

• Will the rotor injure or harass fish and marine mammals? Fluidic impact of

energy extractionFluidic impact of energy extraction

• Will turbine operation alter sedimentation patterns?

• Will flow rates in the estuary be reduced?

• Will the tidal range be altered?

Ecological implications of fluidic impacts

Ecological implications of fluidic impacts

• Mudflat ecosystems?

• Oxygen levels in south Sound and Hood Canal?


Agenda




• UW Research


Research Question: How much tidal energy can be extracted?

003,09-07-06,SNOPUD.ppt

Case StudyCase StudyExtraction Limits

- Balancing Resource Against Fluidic Impact -UW ResearchUW Research

Admiralty Head

Point Wilson

Bush Point

Marrowstone Point

Indian Island

• How much kinetic energy can be extracted by an array?

― Current estimates are 15% of kinetic energy in a channel (little physical reasoning)

― Preliminary results indicate limits are site specific, but also indicate it may be possible to “tune” turbines to site to minimize impact

• Does the construction of one array preclude

the construction of others?― Can 20+ MW arrays be built at Pt. Wilson,

Marrowstone and Bush Point?― Can an array be built at Admiralty Inlet if

one already operating in Tacoma Narrows?

• Building an understanding with 1-D models― Validating 1-D results― 2-D modeling work planned in conjunction

with SnoPUD

?

?

?

tidal in-stream energy overview

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