the future of geothermal energy -- can it become a major...

Jeff TesterCroll Professor of Sustainable Energy Systems

School of Chemical and Biomolecular

EngineeringDirector of the Cornell Energy Institute

and Associate Director for Energy

Cornell Center for a Sustainable Future Cornell Universityjwt54@cornell .edu

607-254-7211

Geothermal energy today resources from hydrothermal systems to hot dry rock applications for direct heating/cooling and electricity

An assessment of US potential Lessons learned in 30+ years of progress on EGS technology A pathway to universal heat mining with technology improvements

The Future of Geothermal Energy --

Can it become a major supplier of primary energy in the U.S.?

Utilization of Geothermal Energy 1.

For Electricity --

As thermal energy for generating electricity2.

For Heating --

direct use of the thermal energy in district heating or in industrial processes

3.

For Geothermal Heat Pumps –

as a source or sink of moderate temperature energy in heating and cooling applications

Earth’s Geosphere

Looking to “inner space”

for opportunities in the Earth’s Geosphere

Accessible Pressure –Temperature DomainEarth’s Geosphere

Geothermal energy in use today

• An accessible, sufficiently high temperature rock mass underground

• Connected well system with ability for water to circulate through the rock mass to extract energy

• Production of hot water or steam at a sufficient rate and for long enough period of time to justify financial investment

• Means of directly utilizing or converting the thermal energy to electricity

Geothermal systems –

common characteristics and limitations

Hydrothermal Reservoirs

Geothermal started producing electricity in Italy at Larderello

in 1904 over 100 years ago

• In 50 years Iceland has transformed itself from a country 100% dependent on imported oil to a renewable energy supply based on geothermal and hydro

• >95% of all heating provided by geothermal district heating

• >20% of electricity from geothermal – remainder from hydro

• 2 world scale aluminum plants powered by geothermal

• Currently evolving its transport system to hydrogen/hybrid/electric systems based on high efficiency geothermal electricity

Geothermal has enabled Iceland’s transformation

Condensers and cooling towers, The Geysers, being fitted with direct contact condensers developed at NREL

The Blue Lagoon in Iceland

Today there are over 11,000 MWe

on-line or under construction--

USA --

4000+ MWe

up from 2544 MWe

in 2005

Total installed by December 2009 –

11,000 MWe

A.S. Batchelor, 2005; Bertani,2008; and GEA, 2009

How is Mexico doing?

Luis C.A. Gutiérrez‐Negrín1,3, Raúl Maya‐González2 and

José

Luis Quijano‐León3

1Geocónsul, 2Comisión Federal de Electricidad, 3Mexican Geothermal Association. Mexico

Session 5E: Country updates

Mexican Volcanic Belt

Los Azufres 188 MW

Cerritos Colorados (Potential: 75 MW)

Cerro Prieto 720 MW

Los Humeros 40 MW

Las Tres Vírgenes 10 MW

• Total geothermal‐electric

installed capacity (net): 958

MW• Total electric generation

in 2009: 6,793 GWh• National average CF:

80.9%• Fields and power units are

owned and operated by CFE

Total: 51,718 MW

• From its beginning in the Larderello Field in Italy in 1904, over 11,000 MWe of on-line capacity worldwide today

• Additional capacity with direct use and geothermal heat pumps (e.g >100,000 MWt worldwide)

• Current costs -- 7–10¢/kWh• Attractive technology for

dispatchable, base load power for both developed and developing countries

Geothermal energy today for heat and electricity

Condensers and cooling towers, The Geysers, being fitted with direct contact condensers developed at NREL

But geothermal today is limited tohigh grade, high gradient sites with existing

hydrothermal reservoirs !!

Enhanced/Engineered Geothermal Systems (EGS) could provide a pathway to universal heat mining

EGS defined broadly as engineered reservoirs that have been stimulated to emulate the production properties of high grade

commercial hydrothermal resources.

Average surface geothermal gradientfrom Blackwell and Richards, SMU (2006)

A range of resource types and gradeswithin the geothermal continuum

• Hydrothermal• Conduction-dominated

EGS• Volcanic EGS• Co-produced fluids• Geopressured

6

Three critical ingredients for successful heat mining 1. sufficient temperature

at reasonable depth2. sufficient permeability 3. sufficient hot water or

steam

The Future of Geothermal Energy

Environmental concerns and benefits

Benefits Land use – small “footprint” compared to alternatives Low emissions, carbon-free base load energy No storage or backup generation needed Adaptable for district heating and co-gen / CHP applications

Concerns Induced seismicity must be monitored and managedWater use –

will require effective control and

management, especially in arid regions

Ormat’s

5 MWe

organic binary plant in Nevada operates with no cooling water consumption!

Water availability and proper water management are important in certain regions

The footprint of geothermal power developments is small

Source -

The Future of Geothermal Energy, MIT report (2006)

Effect of Geothermal Deployment (EGS) on CO2 Emissions from US Electricity Generation1,2

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Curren

t

100 G

W E

GS20

0 GW

EGS

300 G

W E

GS

Curren

t

100 G

W E

GS20

0 GW

EGS

300 G

W E

GS

Curren

t

100 G

W E

GS20

0 GW

EGS

300 G

W E

GS50

0 GW

EGS

Bill

ion

Met

ric T

onne

s of

CO

2 pe

r yea

r

2006 EIA3

4092 TWh Generation1.0 TWe Capacity

2030 EIA Projection3


Constant Growth to 2100Assuming 2030 Energy Mix


Notes: 1. 95% capacity factor assumed for EGS 2. Assumes EGS offsets CO2 emissions from Coal and Natural Gas plants only 3. EIA Annual Energy Outlook 2007 15

The Geothermal Option –A undervalued opportunity for the US

?

Is there a feasible path from today’s hydrothermal systems with 3000 MWe

capacity to tomorrow’s Enhanced Geothermal Systems (EGS) with 100,000 MWe

or more capacity by 2050 ?

Average surface geothermal gradientfrom Blackwell and Richards, SMU (2006)

Hydrothermal

EGS


Transitioning from Today’s Hydrothermal Systems toTomorrow’s Engineered Geothermal Systems (EGS)

An MIT–

led study by an 18-

member international panel

--

Primary goal: to provide an independent and comprehensive evaluation of EGS as a major US primary energy supplier

--

Secondary goal: –

to provide a framework for informing policy makers of what R&D support and policies are needed for EGS to have a major impact

Full report available athttp://www1.eere.energy.gov/geothermal/

future_geothermal.html

1.

Retirements of old coal and nuclear units

In the next 15 to 20 years 40 GWe of “old” coal-fired capacity will need to be retired or updated because of a failure to meet emissions standards

In the next 25 years, over 40 GWe of existing nuclear capacity will be beyond even generous re-licensing procedures

2.

Projected availability limitations and increasing prices for natural gas

are not favorable for large increases in electric generation capacity for the foreseeable future

3.

Public resistance to expanding nuclear power

is not likely to change in the foreseeable future due to concerns about waste and proliferation. Other environmental concerns will limit hydropower growth as well

4.

High costs of new clean coal plants

as they have to meet tightening emission standards and may have to deal with carbon sequestration.

5.

Infrastructure improvements

needed

for interruptible renewables including storage, inter-connections, and new T&D are large

A key motivation --

US electricity capacity is now at 1 TWe

(1,000,000 MWe) and threatened

Geothermal provides base load, dispatchable

power

Multidisciplinary EGS Assessment Team

Panel Members Jefferson Tester, chair, Cornell & MIT, chemical engineer Brian Anderson, University of West Virginia, chemical engineer Anthony S. Batchelor, GeoScience, Ltd, rock mechanics and geotechical engineer David Blackwell, Southern Methodist University, geophysicist Ronald DiPippo, power conversion consultant, mechanical engineer Elisabeth Drake, MIT, energy systems specialist, chemical engineer John Garnish, physical chemist, EU Energy Commission (retired) Bill Livesay, Drilling engineer and consultant Michal Moore, University of Calgary, resource economist Kenneth Nichols, Barber-Nichols, CEO (retired), power conversion specialist Susan Petty, Black Mountain Technology, reservoir engineer Nafi Toksoz, MIT, seismologist Ralph Veatch, reservoir stimulation consultant, petroleum engineer

Associate Panel Members Roy Baria, former Project Director of the EU EGS Soultz Project , geophysicist Enda Murphy and Chad Augustine, MIT chemical engineering research staff

Maria Richards and Petru Negraru, geophysists, SMU Research Staff

Support Staff Gwen Wilcox, MIT


Estimated Temperaturesat Specific Depths

7

U.S. Geothermal resource is large and underutilized

1 EJ = 10+18

J or about 10+15

BTUAnnual US energy consumption = 100 EJ

Estimated total geothermal resource base and recoverable resource given in EJ or 10+18 Joules.

1,000,000 EJ10,000 x US use

A key question -- how much could be captured and used?


30+ Year History of EGS Research

EGS COREKNOWLEDGE

BASE

CooperBasin

(Australia)

FentonHill(USA)

Soultz(EU)

Rose-manowes

(UK)

Hijiori

&Ogachi

(Japan)

FutureUS EGSProgram

Coso,DesertPeak(US)

Basel(Swiss)

Landau(German)

TBD

Developing stimulation methods to create a well-connected reservoir

The critical challenge technically is how to engineer the system to emulate the productivity of a good hydrothermal reservoir

Connectivity is achieved between injection and production wells by hydraulic pressurizationand fracturing

“snap shot” of microseismic events duringhydraulic fracturing at Soultz from Roy Baria

Mapped microseismic

events plotted in plan view during hydraulic stimulation in

the Cooper Basin In Australia

Scale in meters

Large stimulated reservoirvolumes are created byhydraulic pressurization

EGS Reservvoir

at Soultz, France from Baria, et al.

• Fenton Hill, Los Alamos US project• Rosemanowes, Cornwall, UK Project• Hijori, et al , Japanese Project• Soultz, France EU Project• Cooper Basin, Australia Project, et al.

• directional drilling to depths of 5+ km & 300+oC• diagnostics and models for characterizing size and

thermal hydraulic behavior of EGS reservoirs• hydraulically stimulate large >1km3 regions of rock• established injection/production well connectivity

within a factor of 2 to 3 of commercial levels• controlled/manageable water losses• manageable induced seismic and subsidence effects• net heat extraction achieved

R&D focused on developing technology to create reservoirs That emulate high-grade, hydrothermal systems

30+ years of field testing at

has resulted in much progress and many lessons learned

1. Commercial level of fluid production with anacceptable flow impedance thru the reservoir

2. Establish modularity and repeatability of the technology over a range of US sites

3. Lower development costs for low grade EGS systems

A robust research program in geoscience

and

engineering would contribute significantly to:• better characterization of in situ stresses and fracture propagation mechanisms

• improved hydraulic stimulation procedures• enhanced fracture mapping with improved

reservoir connectivity

• better understanding of induced seimicity• improved models of thermal hydraulic

performance

• improved understanding of borehole

breakout mechanisms and stability issues

Although much has been accomplishedthere are a few things left to do

And today the Australians are making progress

Cooper Basin geothermal resource. One of the best sites in world

for Hot Fractured Rock (HFR) geothermal electricity generation -

potential for 1000’s MW generating capacity.

in 2008 --

2010 Wellhead flow rate 18 kg/s

at 275 bar, 208 -

250 oC

And the Australians are continuing to make progress

0

20

40

60

80

100

% of

TotalCost

High GradeHydrothermal (<3 km)

Mid-Grade EGS (3-6 km)

Low Grade EGS (6-10 km)

Drilling and Reservoir Stimulation Power Plant

As EGS resource quality decreases, drilling and stimulation costs dominate

But the economics of EGS still need to be proven

Major impact with higher uncertainty and risk --• Flow rate per production well (20 to 80 kg/s )• Thermal drawdown rate / redrilling-rework periods (3% per year / 5-10 years)• Resource grade – defined by temperature or gradient = f(depth, location)• Financial parameters

• Debt/Equity Ratio (70/30 to reflect industry practice)• Debt rate of return (5.5 -8.0%)• Equity rate of return (17%)

• Drilling costs

Lesser impact but still important --• Surface plant capital costs• Exploration effectiveness and costs • Well field configuration -- 5 production wells / 4 injection wells• Flow impedance• Stimulation costs • Water losses • Taxes and other policy treatments

Factors controlling the economics of EGS

Parametric analysis of capital and levelized

electricity costs (LEC) : 1. Drilling depths: 3 km to 10 km2. Average temperature gradients from 10°C per km to 100°C per km 3. Production well flow rates of 20, 40, 60, 80 and 100 kg/s. 4. Geofluid production temperatures : 100°C - 400°C5. Six different drilling cost cases6. Two electricity price scenarios

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8

10

12

10 100 1,000 10,000 100,000EGS Capacity Scenario (MWe)

Bre

ak-e

ven

Pric

e (¢

/kW

h)

MIT EGS model predictions with today’s drilling and

plant costsand mature reservoir

technology at 80 kg/s per production well

EGS supply curve

Economics of EGS –

sensitivity analysis and supply curve projections

DOE Workshop June 7, 2007 The Future of Geothermal EnergyHigh impact levels for EGS are estimated with a modest investment

for research, development and deployment over a 15 year period

Supply Curve for EGS Electricity

From Blackwell and Richards (June, 2007)

In simpler terms, with EGS working at depths to 6 kmall of the US becomes a viable geothermal resource

ACOCULCO ‐

‐

2 wells

about

2 km

deep

where

drilled

by CFE‐

Very

high

temperatures

( >300oC) ‐

But

very

low

permeability

–

requires

stimulation

Opportunities exist in Mexico for high grade EGS geothermal resourcessuitable for electric power generation

ACOCULCO‐Two

deep

wells

finished

in granite. Very

high

temperature

but

low

permeability

‐With

EGS

techniques

it

could

be fractured

to

increase

permeability

in

the

nearby

reservoir

of

both

wells

to

produce

some7 MW each

‐Or

to

build

a EGS by

hydraulic

fracturing

to

form

adoublet. Inject

water

in one

and

recover

steam

in the

other


1.

Large, indigenous, accessible base load power resource – 14,000,000 EJ of stored thermal energy accessible with today’s technologies. Key point -- extractable amount of energy that could be recovered is not limited by resource size or availability

2.

Fits portfolio of sustainable renewable energy options

- EGS complements the existing portfolio and does not hamper the growth of solar, biomass, and wind in their most appropriate domains.

3. Scalable and environmentally friendly

– EGS plants have small foot prints and low emissions – carbon free and their modularity makes them easily scalable from large size plants.

4. Technically feasible

-- Major elements of the technology to capture and extract EGS are in place. Key remaining issue is to establish inter-well connectivity at commercial production rates – only a factor of 2 to 3 greater than current levels.

5.

Economic projections favorable

for high grade areas now with a credible learning path to provide competitive energy from mid- and low-grade resources

6.

Deployment costs modest

-- an investment of $200-400 million over 15 years would demonstrate EGS technology at a commercial scale at several US field sites to reduce risks for private investment and enable the development of 100,000 MWe.

7.

Supporting research costs reasonable

– about $40 million/yr needed for 15 years -- low in comparison to what other large impact US alternative energy programs will need to have the same impact on supply.

Summary of major findings


Recommended path for enabling 100,000 MWefrom EGS by 2050

Support site specific resource assessment

Support 3-5 field EGS demonstrations at commercial-

scale production rates

Short term --

develop high grade EGS sites at the margins of hydrothermal reservoirs and in high gradient regions at depths of 3 to 6 km for power generation

Longer term develop lower grade EGS sites requiring deeper heat mining at depths >6 km for co-generation

Maintain vigorous R&D effort on subsurface science, geo-engineering, drilling, energy conversion, and systems analysis for EGS

Invest a total of $1000 million for deployment assistance and for research, development and demonstration over 10 years

Less than the price of one clean coal plant !And, provide a comparable amount of R&D support for conventional hydrothermal

Advanced Geothermal TechnologiesAdvanced Geothermal Technologies

1. Expanding direct use and cogeneration with lower grade resources

2. Spallation drilling using hydrothermal flames and jets --

MIT/ETH/Cornell

3. Increasing efficiency by going deeper to supercritical conditions (Icelandic IDDP)

4. Ultra high grade geothermal energy from submarine hydrothermal vents (Mexico, Hiriart, et al)

Pools, etc.

Comm.Space

Heating

Resid.Water Heating

Comm.WaterHeating

Comm. AC

Clothes Dryer

Resid.SpaceHeating

Resid. Refrig.

Industrial Process Steam

Resid. AC

Cooking

Opportunities for direct use below 250oC are substantial

Represents about 35% of total US demand in 2008

Fox, Sutter, Tester (2010)

US Energy demand versus temperature

Example 1 Advanced technology for continuous drilling

using thermal spallation/fusion

Low density oil-air flame drilling in open boreholes

Hydrothermalflames at

high density

usingCH4

, H2

, CH3

OH

Spallation drilling using hydrothermal jets

Flame jet spallation atatomspheric

pressures

• Visible combustion flames produced in a supercritical water environment ( P > 220 bar)

• Temperature at center of flame can reach over 3000 K, but subcritical water temps at wallsT ~ 2500 K/cm)

• Hydrogen, methanol and methane fuels considered

Research focus is on experimental and theoretical studies of hydrothermal flames and jets in supercritical water.

Contributing researchers –

Chad Augustine and Hildigunnur

Thorsteinssonand Prof. Philip von Rohr and colleagues at ETH in Zurich

Our research is extending spallation/fusion drilling to deep well drilling using hydrothermal jets

Drilling Costs –Actual and Predicted

Actual oil and gas well costs

JAS database

Actual geothermal well costsMIT and Sandia databases

Livesay

WellCost

Lite

model EGS well predictions +/-

25%

Advanced drilling technologies cases1-3

NB –normalization to 2004 $ using MIT drilling cost index


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Wel

lcos

t Lite

+25

%W

ellc

ost L

ite B

ase

Wel

lcos

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Cas

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lcos

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+25

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ellc

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ase

Wel

lcos

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ellc

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lcos

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Cas

e 1

Cas

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Cas

e 3

LEC

cen

ts/k

Wh

LEC - this study

Base Case Feasibility at 2050

High Case Feasibility at 2050

Predicted Breakeven Electricity Prices(LEC) 5 km and 60°C/km -

20 kg/s

60 kg/s 80 kg/s


Levelized energy costs vary with resource grade and reservoir productivity and drilling costs

223.4¢

41.1¢

18.0¢ 13.2¢

64.3¢

12.9¢6.3¢ 5.3¢

32.3¢

7.6¢ 4.1¢ 4.3¢

0

50

100

150

200

250

20°C/km 40°C/km 60°C/km 80°C/km

Average Temperature Gradient

LEC

¢/k

Wh

Today's drilling technologywith 20 kg/s flow rate

Today's drilling technologywith 80 kg/s flow rate

Advanced drilling technologywith 80 kg/s flow rate

6 km depth

6 km depth

6 km depth 4 km depth


Geothermal energy in use today

High efficiency electric power at supercritical conditions

Iceland moves toward utilizing supercritical geothermal water

Iceland’s natural supercritical water region

If IDDP is successful it will enable a new generation of ultra high efficiency geothermal power generation

What

do we

know now

about

Ocean

Ridges

• There

are 67,000 km

of

Ocean

Ridges,

representing

30% of

all

heat

released

by the

earth

• 13,000 km

have

been

already

studied,

representing

20% of

the

Ridges

of

the

World

• 280 sites

of

geothermal

vents

have

been

discovered, representing

3,900

km

of

active vents

• Baker

has reported

“…up to

100 km

of

uninterrupted

vents…”

…. some

of

them

with

a thermal

power

of

up to

6,000 MWt…

• What

if

we

use only

1% of

the

known

vents

to

generate

electricity?

67,000 KmOcean

Ridges

13,000 KmExplored

3,900 Km

With

good

vents

1 % usable 39 km

!

T = 250°CTsink

10°C

10 cm

1 m

V = 1 m/s

Q= 240x4187x1x0.1=100 MWt

/m

Thermal

power

of

an

hydrothermal

vent

45% Carnot 90% Turbine

η

=10 %

Total transformation

efficiency

(0.1x0.45x0.90)

η

= 4

%

Specific

Electric Power= 100 MWt

x 0.04 = 4 MW/m

Total Electrical

Power

in 39 km……156 000 MW!!

Schematic representation of a binary submarine generator

Thank you for listeningThank you for listening

Please read our report athttp://www1.eere.energy.gov/geothermal/future_geothermal.html

Acknowledgements

We are especially grateful to the US DOE for its sponsorship and

to many members of US and international geothermal community for their assistance, including Roy Mink, Allan Jelacic, Joel Renner,Jay

Nathwani, Greg Mines, Gerry Nix, Martin Vorum, Chip Mansure, Steve Bauer, Doone

Wyborn, Ann Robertson-Tait, Pete Rose, Colin Williams, Mike Wright, Roland Horne, Hidda

Thorsteinsson

and Valgardur

Stefansson

Acknowledge Support for the Project provided by the Geothermal Division and its Laboratories

Idaho National Laboratory

National Renewable Energy Laboratory

Sandia National Laboratories

the future of geothermal energy -- can it become a major...

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