Chuck KutscherNational Renewable Energy Laboratory

Geothermal Power Potential

Energy and Climate Mini-WorkshopNovember 3, 2008

Source: EIA Annual Energy Review 2007

Geothermal in the Energy Portfolio Net Generation – 2006

U.S. Renewable Energy Electric Capacity

Sources: Chalk, AWEA, IEA, NREL, EIA, GEA

Geothermal Resources

Hot granite

Geopressured

Enhanced Geothermal System

Hot water

Wells

Magma

Volcanic

Hydrothermal

Carbon Benefits

Advantages of Geothermal EnergyAdvantages of Geothermal Energy

• Environmentally sound

• Resources last the life of the plant

• High plant availability (over 95%)

• Provides steady base load power

• Relatively low cost (5 to 8 cents per kWh)

Today’s Status

• 8,000 MW generated in 21 countries

• In U.S. 3,000 MWe installed, 4,000 MWe under development

• DOE funding 21 companies $43 million over 4 years for EGS projects

• Cost 5-8¢/kWh with no PTC

• Capacity factor typically > 90%, base load power

G E O T H E R M A L

G E O T H E R M A L

Hydrothermal ResourceHydrothermal Resource

Geothermal Power Plants

Plant Type vs. TemperaturePlant Type vs. Temperature

0oC32oF)

90oC(195oF)

175oC(350oF)

Flash steam

Binary cycle

G A 0 2 - 5 0 6 8 3 - 2 2

Generator

Steam

ProductionWell

InjectionWellGeothermal Zone

Waste Brine

Water

Air and Water Vapor

Air

DirectHeatUses

Air

G A 0 2 - 5 0 6 8 3 - 2 4

Generator

Iso-Butane

ProductionWell

InjectionWellGeothermal Zone

Water

Heat Exchanger

Air and Water Vapor

Air

Pump

Air

Water

CoolBrine

Condenser

Plant CostsPlant Costs

Flash ($/kW)

Binary ($/kW)

Exp./drilling 700 500

Equip. 750 1600

TOTAL 1,450 2,100

Favorable Geothermal Areasand Known Systems

Geographic Distribution of Hydrothermal Resources

Identified Geothermal Resources Undiscovered Resources

USGS, 2008

U.S. Hydrothermal Electric Power Potential

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

95 50 5 Mean

Percent Confidence

Po

ten

tia

l (M

We

)

Undiscovered

Identified

Williams, et al., USGS Fact Sheet, “Assessment of Moderate- and High-TemperatureGeothermal Resources of the United States,” September 2008

Heat

Fluid Content Permeability

Geothermal Domains

Enhanced Geothermal

System

Hot Dry Rock(HDR) – Fracturingand water injectionrequired

Note: System must have fluid content, permeability, and heat to be potentially viable. This combination can be natural (Hydrothermal) or created in an enhanced geothermal system.

Water InjectionRequired

FracturingRequired

Hydrothermal

Geographic Distribution of EGS

USGS, 2008

EGS ResourceTemperatures at 6 km Depth

EGS Steps

Source: NREL

The U.S. Enhanced Geothermal System Resource

Source: MIT Study- TheFuture of Geothermal Energy

MIT EGS Supply Curve:10% of U.S. Capacity by Mid-Century

0

2

4

6

8

10

12

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

Bre

ak-e

ven

Pri

ce (

¢/k

Wh

)

MIT EGS model predictions with today’s drilling and plant costsand mature reservoir technology at 80 kg/s per production well

2004 US $

EGS Challenges

Technical• Site selection - regional exploration

techniques for EGS• Creating EGS under various geologic

environments– achieving low flow impedance– achieving sufficiently large

sustainable reservoir without short circuiting (80 kg/s at 200°C)

– minimizing water loss– microseismicity

• Few EGS field experiments yet conducted worldwide; only 25 kg/s achieved at Soultz

Geologic variability and uncertainty make the technical challenges of EGS very different from other

renewable energy sources.

Economic• Exploration cost and risk• Drilling, completion and reservoir stimulation costs• Capital cost of surface facilities• No commercial EGS site for benchmarking

Commercialization• Validating EGS technology requires high risk field

experiments in a variety of geologic settings• Limited Federal R&D funding

EGS Challenges

U.S. EGS Electric Power Potential

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

95 50 5 Mean

Percent Confidence

Po

ten

tia

l (M

We

)

Williams, et al., USGS Fact Sheet, “Assessment of Moderate- and High-TemperatureGeothermal Resources of the United States,” September 2008

ASES Study Supply Curve

Geothermal Supply Curves(Petty, Porro)

0

2

4

6

8

10

12

14

16

18

20

- 20 40 60 80 100

Cumulative Capacity (GW)

LC

OE

(2

004 ¢

/ k

Wh)

current technology basis

with projected DOE gains

Bases for market penetration studies using NEMS.

Hydrothermal 27 GWSedimentary EGS 25 GWCo-produced fluids 44 GWBasement EGS 4 GW

Geothermal Power Savings

Carbon Savings: 83 MtC/yr

• 50,000 MW by 2030• 25% existing resources, 25% expanded,

50% from oil & gas wells• 5 to 10 ¢/kWh