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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