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GEOTHERMAL GEOTHERMAL POWERPOWER
Ken WilliamsonKen Williamson
General Manager, General Manager, Geothermal Technology & Services,Geothermal Technology & Services,
Unocal CorporationUnocal Corporation
WORKSHOP ON SUSTAINABLE ENERGY SYSTEMSNovember 29 - December 1, 2000
Georgia Tech, Atlanta, GA
GEOTHERMAL GEOTHERMAL POWERPOWER
Ken WilliamsonKen Williamson
General Manager, General Manager, Geothermal Technology & Services,Geothermal Technology & Services,
Unocal CorporationUnocal Corporation
WORKSHOP ON SUSTAINABLE ENERGY SYSTEMSNovember 29 - December 1, 2000
Georgia Tech, Atlanta, GA
Heat in the EarthHeat in the Earth (Rybach et al., 2000)(Rybach et al., 2000)
Stored in the earthStored in the earth 10 103131 J J
Beneath continents (<1km) 4.10Beneath continents (<1km) 4.102626JJ
Current Annual UsageCurrent Annual Usage 4.10 4.102020JJ
Geothermal Power WorldwideGeothermal Power Worldwide
8 GW8 GWee in 21 nations in 21 nations
50 TWh 50 TWh generated in 1999
In the last 5 years:– Worldwide increased by 17%– U.S. decreased 20%
Geothermal Power in U.S.Geothermal Power in U.S.0.38% of Country’s Generation0.38% of Country’s Generation
CaliforniaCalifornia 2,294 MW2,294 MW NevadaNevada 196 MW 196 MW HawaiiHawaii 25 MW 25 MW UtahUtah 31 MW 31 MW
TOTAL TOTAL 2,400 MW2,400 MW
HIGH ENTHALPY FIELDS & HIGH ENTHALPY FIELDS & PROSPECTSPROSPECTS
Pacific “Ring of
Fire”
Pacific “Ring of
Fire”
Exploration
“Oil seep” analogy
Geothermal Fields Geothermal Fields Developed by UnocalDeveloped by Unocal
GeysersGeysers
1100 MW1100 MW
IndonesiaIndonesia
330 MW330 MW
PhilippinesPhilippines
756 MW756 MWSalton SeaSalton Sea
80 MW80 MW
Geothermal BasicsGeothermal BasicsExtracting the Heat CommerciallyExtracting the Heat Commercially
Water transports heat to surfaceWater transports heat to surface
Naturally fractured rock permits circulationNaturally fractured rock permits circulation
Drill to reach at least 200° CDrill to reach at least 200° C
Future technology may use man-made Future technology may use man-made fracturesfractures
GEOTHERMAL RESOURCE TYPESGEOTHERMAL RESOURCE TYPES
Liquid-Liquid-dominateddominated
Vapor-Vapor-dominateddominated
Low EnthalpyLow Enthalpy
Hot Dry RockHot Dry Rock
Example: Vapor-Dominated Example: Vapor-Dominated High Enthalpy ResourceHigh Enthalpy Resource
Unocal at The Geysers Unocal at The Geysers 1967 -19991967 -1999
380 wells drilled2.5 trillion lbs steam produced124 billion kWh generated
186 million bbl oil equiv.
Example: Liquid-Dominated Example: Liquid-Dominated High Enthalpy ResourceHigh Enthalpy Resource
Medan
S u m a t r a
Kalimantan Sulawesi
Jakarta
SALAK PROJECT
330 MW
JAVA
SALAK PROJECT
INDEX MAP
100KM0
SCALE 1:30.000.000
Unocal 330 MW in Java, Indonesia
Liquid-dominated 225 - 310º C
1 - 3 km deep
CROSS-SECTION THROUGH AWIBENGKOK FIELD
During Project Life:
Produce >10 12 lbs steam
Inject 16 billion bbl brine
TurbineandGenerator
Proposed Research TimelineProposed Research Timeline2000 - 20302000 - 2030
» Optimize exploited geothermal systems & Optimize exploited geothermal systems & reduce development cost of high enthalpy systemsreduce development cost of high enthalpy systems
» Locally enhance permeability in the tight margins Locally enhance permeability in the tight margins of existing systems (EGS)of existing systems (EGS)
» Explore for and develop “hidden” high Explore for and develop “hidden” high enthalpy systems, with no surface featuresenthalpy systems, with no surface features
» Develop impermeable systems with Develop impermeable systems with artificial fracturing (HDR)artificial fracturing (HDR)
-----> Time-----> Time
Optimize exploited geothermal Optimize exploited geothermal systemssystems
Life Cycle of a Geothermal Field Life Cycle of a Geothermal Field (Lovekin, 1998)(Lovekin, 1998)
Time ---->
develop maintain decline sustain
MW
OpportunityOpportunity
Only a fraction (~20%) of available heat is Only a fraction (~20%) of available heat is currently extracted from a high enthalpy currently extracted from a high enthalpy reservoirreservoir
Smart injection management could greatly Smart injection management could greatly increase efficiency and longevityincrease efficiency and longevity
The Salak “natural laboratory” presents a The Salak “natural laboratory” presents a unique opportunity to examine fractured-unique opportunity to examine fractured-system behaviorsystem behavior
ChallengeChallenge
Reservoirs have km-scale fracturing: Reservoirs have km-scale fracturing: » hard to map permeability at km-scalehard to map permeability at km-scale» heat transfer properties poorly knownheat transfer properties poorly known» current models inadequatecurrent models inadequate
Injected liquids are channeled along fractures Injected liquids are channeled along fractures and heat sweep is inefficientand heat sweep is inefficient
Research: Research:
Characterize permeability and heat Characterize permeability and heat transfer in fractured systemstransfer in fractured systems
Image Log: Salak Well FMIImage Log: Salak Well FMI
12
U1,2,3
U4,5,6
0 1 Km
Salak Tracer pathways
AWI 4-1 TRACER RETURNS AT AWI 1 WELLS
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-20 0 20 40 60 80 100
Elapsed Time since Dye Injection on 1/8/99, day
Co
ncen
trati
on
, p
pb
1-3
1-4
1-5
1-6
1-7
Tracer Returns at Salak
Proposed Research: Proposed Research: Designer tracer cocktailsDesigner tracer cocktails
average path temperatureaverage path temperature
maximum path temperaturemaximum path temperature
surface contact area along flow pathsurface contact area along flow path
0
SALAK NUMERICAL MODEL FEATURES
WESTERN OUTFLOW
NORTHERN OUTFLOW
SOUTHERN OUTFLOW
SHALLOWEASTERN RESERVOIR
DEEP WESTERNRESERVOIR
Technical Challenge:Technical Challenge:
Combine sparse, complex Combine sparse, complex data to predict heat sweep in data to predict heat sweep in
naturally fractured systemsnaturally fractured systems
Reduce development cost of high Reduce development cost of high enthalpy systemsenthalpy systems
Reducing development costsReducing development costs
Drilling TechnologyDrilling Technology
Energy Conversion TechnologyEnergy Conversion Technology
ChallengesChallenges
Need active continuous drilling Need active continuous drilling programs to create improvements in programs to create improvements in drillingdrilling
Geothermal industry too small to attract Geothermal industry too small to attract research in service companiesresearch in service companies
Geothermal turbines are not designed Geothermal turbines are not designed and built in the U.S.and built in the U.S.
OpportunitiesOpportunities
Sandia and developers collaborate in Sandia and developers collaborate in drilling technologydrilling technology
Remarkable drilling improvements have Remarkable drilling improvements have occurred - more are possibleoccurred - more are possible
Drilling Cost Reduction at SalakDrilling Cost Reduction at Salak
75
64
44
27
0
10
20
30
40
50
60
70
80
Units 1 & 2 1995 1996 1997
DAYS PER WELLAWIBENGKOK EXPANSION
GeothermalGeothermal
The BenefitsThe Benefits
Power Plant COPower Plant CO22 Emissions Emissions
0
100200
300
400500
600
700
800900
1000
CO
2 (
kg/M
Wh
) Coal
Oil
Natural Gas
UnocalGeothermal
Fossil fuel data from Goddard and Goddard (1990)Unocal data includes The Geysers
Capacity FactorsCapacity Factors
Source: DOE/Energy Information Agency: data for 1996Source: DOE/Energy Information Agency: data for 1996
0
20
40
60
80
100
WindWind SolarSolar Conv.Conv. AverageAverage Biomass/Biomass/ FossilFossil GeothermalGeothermal
HydroHydro MSWMSW
PercentagePercentage
U.S. Government RoyaltiesU.S. Government Royalties
0
50
100
150
200
Wind Solar Biomass Geothermal
$ Millions$ Millions
ConclusionsConclusions
Ultimate geothermal resource is hugeUltimate geothermal resource is huge Present research focus should be:Present research focus should be:
– extend life of existing fields, extend life of existing fields, – reduce cost of developing new high enthalpy reduce cost of developing new high enthalpy
projectsprojects
Artificially stimulated systems (HDR/EGS) Artificially stimulated systems (HDR/EGS) hold greatest opportunity in the long term hold greatest opportunity in the long term
HDR/EGS research should focus on HDR/EGS research should focus on technology which can be tested in existing technology which can be tested in existing fieldsfields
The End