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