Geothermal Resources

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Geothermal Resources
Lisa Shevenell Director, Great Basin Center for
Geothermal Energy
Dixie Valley, NV
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What is geothermal?

• Areas where energy can be tapped due to high heat
  flow in the near-surface part of the crust (upper
  5 km)
• Uses of geothermal various types of space
  heating, aquaculture, food dehydration,
  electricity production

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Why geothermal?

• Earth is losing heat continuously to space
• Thermal energy produced by decay of radioactive
  elements makes mantle hot, crust hot
• Geothermal areas result from high heat flow in
  upper part of crust where it can be utilized
• Normal geothermal gradient is 25?C/km
• Elevated geothermal gradient in some areas
• Magmatism, thin crust

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The Earth
Crust
Mantle
Outer core
Inner core
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Plate Tectonic Processes
Spreading Center
Continental Plate
Plate
Oceanic
Subducting
Convection
Plate tectonics provide a focusing mechanism for
heat loss
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Velocities cm/yr
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Plate Boundaries
Ring of Fire
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Geothermal Power Plants
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ANATOMY OF A GEOTHERMAL SYSTEM
GEOTHERMAL FEATURE
CONDUITS TO THE SURFACE
fractured rocks
GROUNDWATER RESERVOIR
HEAT SOURCE
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Types of Systems

• Conventional hydrothermal systems
• Extensional
• Magmatic
• Higher T (gt100C) Power
• Lower T (lt100C) Direct Use
• Geopressured systems (Oil Gas Fields)
• Hot dry rock (HDR or EGS)
• Magma (Long Valley)

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Characterization of Natural Geothermal Resources
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NEVADA IS UNDERGOING REGIONAL EXTENSION
EXTENSION DIRECTION
Warmer colors indicate greater dilational
(extensional) strain, as measured by movement
between permanent GPS stations located in the
Great Basin.
Dilational strain map of the Great Basin.
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IDEALIZED CROSS SECTION ACROSS THE BASIN AND
RANGE PROVINCE
Looking ENE
EXTENSION
EXTENSION
RANGE FRONT FAULT
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Formation of Extensional Geothermal Systems
CARTOON CROSS SECTION THROUGH BASIN AND RANGE
LOOKING ENE
Cold Groundwater
Cold Groundwater
Heated Groundwater
HOT ROCKS
RESERVOIR
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CASE 1 Geothermal water follows range front
fault to the surface
Upwelling geothermal fluids
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CASE 2 Geothermal water gets entrained in
surface groundwater
Upper SB
Lower SB
Upwelling geothermal fluids
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Effects of extensional tectonics in Nevada
Fault scarp from 1915 Pleasant Valley quake,
Nevada range front fault

• As the crust thins, hot rocks get closer to the
  surface, increasing heat flow
• Extension produces copious faulting and
  fracturing that serve as conduits for hot water
  to reach the surface
• Creates conditions where rhyolite magmas and
  magmatic geothermal systems can form

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Engineered Systems

• Hot Dry Rock 1970s and 1980s
• Enhanced Geothermal Systems after 2000

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Hot Dry Rock
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Resource Size and Distribution

• Typically 50-200 MW per site
• Conventional development in Western US
• USGS 1978 estimate 150,000 MW (W US)
• USGS 2006 estimate just beginning

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Hottest Known Geothermal Regions
Plate Boundaries - Hot Spots - Rifts
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Estimated Temperature at 6 km Depth
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U.S. Geothermal Potential (1999)
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2005 Projected MW
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Geothermal electricity generation- base load
First geothermal ? power plant Larderello,
Italy, 1904 Modern cooling tower, Larderello,
Italy, today ?
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Operation and Equipment
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Nevada geothermal power plants, thermal springs
and wells
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Production Well
Injection Well
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Electricity
Steam entry
Coiled wire cylinder
Electrical generation is similar to other power
plants steam-driven turbines
Turbine blades
Magnetic field
Steam outlet
Turbine Generator
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Three types of power plants Dry steam Liquid
flash plants Binary plants
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Geysers power plant, built 1962
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Three types of power plants Dry steam Liquid
flash plants (gt150ºC) Binary plants
Steam
Turbine
Generator
Flash Tank
Electricity
Condensed Steam (Water)
Hot Water
Separated Water
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Nevada Flash Power Plants
Plant Year Output Temp (MW) (C) Beowaw
e 1985 16.7 199 Bradys 1992 21.1 186 Upper
SB 1988 14.4 236 Desert Peak 1985 9.9 205
Dixie Valley 1988 66 250
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Upper Steamboat Power Plant
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Brady Power Partners
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Binary Power Plants

• Organic Rankine Cycle
• Kalina Cycle

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Three types of power plants Dry steam Liquid
flash plants Binary plants (lt150ºC)
Generator
Binary Vapor
Turbine
Electricity
Binary Liquid
Heat Exchanger
Cooled Water
Hot Water
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Nevada Binary Power Plants
Plant Year Output Temp Empire 1987 3.6 151
Soda Lake 1 1987 3.6 182 Soda Lake
2 1991 13 182 Steamboat (I,Ia) 1986 7.1 170
Steamboat (II,III) 1992 48 170 Stillwater 1
989 13 158 Wabuska 1 1984 0.6 107 Wabuska
2 1987 0.6 107
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Binary generation at Empire Farms (3.6 MW)
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Soda Lake Binary Plant (13 MW)
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Steamboat II, III (48 MW)
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NV Binary Working Fluids

• Soda Lake Plant 1 isopentane
• Plant 2 pentane
• Steamboat I, I-A, II, III isopentane Galena
  I isopentane
• Stillwater isopentane
• Wabuska isopentane

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New Plant 2005

• Galena 1 (Richard Burdette) at Steamboat
• first Plant in gt10 years
• first Plant built after RPS passed
• to produce 20 MW, net, to the grid

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History of Kalina Cycle (ammonia/water working
fluid)
1988 Invention of technology, formation of
Exergy 1990 Start of construction of 6.5 MW
Canoga Park 1991 Startup of Canoga Park (6.5 MW
DOE/Boeing Rocketdyne demo project) 1992-97
Canoga Park Testing (CEC funded) 1999 First
commercial Kalina Cycle Plant operational,
Sumitomo (Japan) 2000 First Kalina power plant
in Iceland, Húsavík
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Combined Cycle Power Plants
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View of Bradys Power Plant and fumaroles from a
distance. Photo Mark Coolbaugh. 2-Nov, 2004
View of Bradys Power Plant and fumaroles from a
distance. Photo by Mark Coolbaugh. 2-Nov
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Other Known Areas - Current Work
Animas Valley (NM) Ormat Blue Mountain Noramax
Corp Fallon NAS Navy Fish Lake
Valley California Energy Pyramid Lake Paiute
Tribe Rye Patch Presco Energy Salt Wells Amp
Resources Steamboat Ormat Tuscarora Earth
Power Resources, Inc. Lake City (CA) Lake City,
LLC
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Power Cycle Performance

• Output depends on
• Initial Fluid T
• Flashing conditions (P and T)
• Turbine efficiencies
• Condensing temperatures

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Efficiencies

• Hi-T steam or direct flash most efficient
• Most binary will be air cooled to minimize water
  use can be 20-30 less efficient in summer
  months

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• Stu Johnson at Ormat
• sjohnson_at_ormat.com
• [phone]

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Size Question from Monday Aerial Resistivity
160 m
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Steamboat Hills (from Skalbeck, 2001)
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Bradys-Desert Peak area color-shaded Interferogram
Period Nov 4, 95 to Sep 24, 00. Each color band
represents 1.6 mm range change over the
interferogram period. Production wells
magenta Injection wells blue Roads thin white
lines
I-80
Bradys
Desert Peak Field
noise
I-80
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Geothermal Anomalies Average Day
Night TIMS band 5 radiance from 5 km with
subtraction for slope aspect albedo With Topo
Shading Anomaly Strength red
strong yellow-green moderate blue
weak (Image courtesy of Mark Coolbaugh) 1
km
Steamboat, NV
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Scaling without inhibitors
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Worldwide Geothermal Direct Use

• Direct uses of geothermal water supply over
  11,000 thermal megawatts in over 40 countries
• Another 35 countries use natural hot springs for
  bathing but have not yet developed their
  geothermal reservoirs for commercial use.

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Space heating Beppu, Japan
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Balneology Mammoth Lakes, CA
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Geothermal agriculture
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Alligators in Idaho!
Fish
Prawns
Farming uses fish, prawns, even alligators
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Direct use for district heating
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• This is a "plate type" heat exchanger which
  passes hot geothermal water past many layers of
  metal plates, transferring the heat to other
  water passing through the other side of each
  plate.

• Principles of a heat exchanger
• Why not just use the hot water directly?

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States Currently Using Geothermal Resources
(direct use, heat, and power)

• Alabama
• Alaska
• Arizona
• Arkansas
• California
• Colorado
• Florida Georgia
• Hawaii
• Idaho
• Louisiana
• Mississippi
• Montana

• Nevada
• New Mexico
• New York
• North Carolina
• Oregon
• South Dakota
• Texas
• Utah
• Virginia
• Washington
• West Virginia
• Wyoming

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Nevada direct use geothermal facilities.
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Nevada Direct Use Facilities
Ash Springs spa Baileys HS spa Bowers
Mansion pool Bradys vegetable
dehydration Caliente spa, pool, space
heating Carson City pool, spa Darroughs
HS spa
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Nevada Direct Use Facilities, Contd
Elko pool, space heating Moana space
heating San Emidio Desert vegetable
dehydration Steamboat spa, space
heating Walleys HS spa Wells geothermal heat
pump
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Other types of geothermal

• Geothermal aquifers heat pumps

Heat pump in winter
Heat pump in summer
Heat is collected from the building
transferred to the ground
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Sustainability

• Meet the needs of the present generation w/o
  compromising needs of future generations (300 yr
  perspective)
• Dependent on initial quantity, rate of generation
  and consumption
• Duration of natural hydrothermal systems
• 5,000 1,000,000 yrs
• Age of waters often old (10,000 yrs in NV)
• Exploitation that exceeds natural recharge
  greatly reduces lifetimes
• Reinjection is key

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Sustainability

• The Geysers
• Dixie Valley

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System Longevity

• Output Power
• Well Density
• Injection Strategy
• Initial Reservoir Pressure
• Initial Fluid Temperature
• Permeability

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Deleterious Environmental Impacts
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Major Environmental Issues, Geothermal Development

• Visual impacts, noise, construction
• Cessation of spring discharge
• H2S pollution of atmosphere
• Brine pollution of environment
• Hydrothermal explosions induced boiling
• Reservoir drawdown, subsidence, interference,
  induced seismicity
• Landslides catastrophic and creeping

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Brine Chemistry (mg/kg)
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SBG - 1986, 1992, 2005 CPI - 1988
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Aquifer WL recovery
Drought 1986-94
50 m from Sage Hill Road Fault
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Prior to Production
Close to Fault
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Farther from Fault
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Mixing Varies Seasonally
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lower thermal water in fall (gtrecharge from
summer irrigation), greater thermal water in
spring
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Summary

• Changes (and static conditions) in waters can be
  a function of interplay of several variables
• Geothermal production
• Injection increased geothermal
• Production decreased geothermal, drying of
  springs
• Drought
• Changes in municipal production
• Changes in irrigation
• Geologic isolation of different waters

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Dixie Valley, Nevada

• Increased fumarole activity, new thermal
  features, dead zone, subsidence during late
  1990s

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Dixie Valley, Recent Fractures
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Subsidence, Wairakei, 1970-1980
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Cumulative Subsidence, Wairakei
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2005 Seismic Activity at the Geysers

• Two quakes over 4.0 on May 8 and 9
• Three between 3.0 and 3.99
• Multiple quakes lt 3.0, often several per day

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Induced Seismicity SE Geysers
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Induced Seismicity, SE GeysersHypocenter Cross
Section
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Zunil Fault, Alteration

• Severe hydrothermal alteration (silica, clays,
  low-T oxides) and fumarolic activity in faulted
  andesite
• Drill pad and roads in fault zone destabilize
  slope

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Zunil Landslide, 1991

• Slide occurs at night buries 35 people alive
• Decapitates 260C geothermal well requires 14
  months to complete repairs
• Locals believe slide caused by well explosion or
  volcanic eruption

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Prevention and Mitigation

• Collection of pre-development background data
• Monitoring of important parameters during
  production (air, water,
• thermal activity, P/T declines, seismicity,
  subsidence, drawdown, etc.)
• Perseverance required

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Beneficial Environmental Impacts
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Freshwater Consumption
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Particulate Matter
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CO2 Emissions
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Status of Technology
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High Drilling Costs

• High temperatures need high density muds
• Larger diameters than oil/gas slim holes
• Harder rock than oil/gas advances in drill bits
• Lost circulation is common foams

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Lower Gradient Greater Drilling Depths
Greater Costs
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Status - Power Plants

• Improvements in size of plants to make them less
  visible
• Kalina Cycle

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Growth in U.S. Geothermal Power
MWe
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Nevada Geothermal Graph

• Requested from Ron

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2004 World Power Production

• United States 2,544 MW
• Philippines 1,931 MW
• Mexico 953 MW
• Indonesia 797 MW
• Italy 790 MW
• Japan 535 MW
• New Zealand 435 MW
• Iceland 202 MW
• Costa Rica 163 MW
• El Salvador 151 MW

• Total for Asia 3,291 MW
• Total for EU members 822 MW
• Total geothermal power production 54.7 TWor 0.3
  of worlds electricity

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Capacity Factor(The ratio of the net electricity
generated, for the time considered, to the energy
that could have been generated at continuous
full-power operation during the same period. )

• Technology Capacity Factor
• Geothermal 97
• Biomass 80
• Wind 26 40
• Solar 22 32

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Advanced Systems

• Primarily HDR / EGS
• Could potentially be applied nation-wide
• Current demonstration projects
• Coso
• Desert Peak
• Long term solution not short term

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R D Needed - HDR

• Improved knowledge of rock mechanics
• Creating fractures
• Keeping fractures open
• Improved assessment of the systems
• Locating and drilling into fractures

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R D Needed - Conventional

• Drilling most expensive part of development
• Identifying productive faults locally
• Reservoir management strategies
• Improved efficiencies in energy conversion
• Improved efficiencies in air cooling of working
  fluids

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Competing in Energy Markets

• Power purchase agreements
• Renewable energy portfolio standards (RPS)
• Production tax credits
• Reduced risk in drilling needed
• Transmission lines
• Increased fossil fuel costs

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Renewable Portfolio Standards (RPS)

• Nevada ( Renewables)
• 2003 8 (met)
• 2013 15
• National ( Renewables)
• 2008 1
• 2009 2
• 2010 3
• 2027 and thereafter 20

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Steamboat Hills in the distance from Geiger
Grade, looking west toward Mt. Rose Photo by
Mark Coolbaugh. 5/17/2003