Geothermal Energy

1
Geothermal Energy

• Stephen Lawrence
• Leeds School of Business
• University of Colorado
• Boulder, CO 80309-0419

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AGENDA Geothermal Energy

• Geothermal Overview
• Extracting Geothermal Energy
• Environmental Implications
• Economic Considerations
• Geothermal Installations Examples

3
Geothermal Overview
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Geothermal in Context
U.S. Energy Consumption by Energy Source,
2000-2004 (Quadrillion Btu)
http//www.eia.doe.gov/cneaf/solar.renewables/page
/geothermal/geothermal.html
5
Advantages of Geothermal
http//www.earthsci.org/mineral/energy/geother/geo
ther.htm
6
Heat from the Earths Center

• Earth's core maintains temperatures in excess of
  5000C
• Heat radual radioactive decay of elements
• Heat energy continuously flows from hot core
• Conductive heat flow
• Convective flows of molten mantle beneath the
  crust.
• Mean heat flux at earth's surface
• 16 kilowatts of heat energy per square kilometer
• Dissipates to the atmosphere and space.
• Tends to be strongest along tectonic plate
  boundaries
• Volcanic activity transports hot material to near
  the surface
• Only a small fraction of molten rock actually
  reaches surface.
• Most is left at depths of 5-20 km beneath the
  surface,
• Hydrological convection forms high temperature
  geothermal systems at shallow depths of
  500-3000m.

http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
7
Earth Dynamics
http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
8
Earth Temperature Gradient
http//www.geothermal.ch/eng/vision.html
9
Geothermal Site Schematic
Boyle, Renewable Energy, 2nd edition, 2004
10
Geysers
Clepsydra Geyser in Yellowstone
http//en.wikipedia.org/wiki/Geyser
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Hot Springs
Hot springs in Steamboat Springs area.
http//www.eia.doe.gov/cneaf/solar.renewables/page
/geothermal/geothermal.html
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Fumaroles
Clay Diablo Fumarole (CA)
White Island Fumarole New Zealand
http//lvo.wr.usgs.gov/cdf_main.htm
http//volcano.und.edu/vwdocs/volc_images/img_whit
e_island_fumerole.html
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Global Geothermal Sites
http//www.deutsches-museum.de/ausstell/dauer/umwe
lt/img/geothe.jpg
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Tectonic Plate Movements
Boyle, Renewable Energy, 2nd edition, 2004
15
Geothermal Sites in US
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Extracting Geothermal Energy
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Methods of Heat Extraction
http//www.geothermal.ch/eng/vision.html
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Units of Measure

• Pressure
• 1 Pascal (Pa) 1 Newton / square meter
• 100 kPa 1 atmosphere 14.5 psi
• 1 MPa 10 atmospheres 145 psi
• Temperature
• Celsius (ºC) Fahrenheit (ºF) Kelvin (K)
• 0 ºC 32 ºF 273 K
• 100 ºC 212 ºF 373 K

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Dry Steam Power Plants

• Dry steam extracted from natural reservoir
• 180-225 ºC ( 356-437 ºF)
• 4-8 MPa (580-1160 psi)
• 200 km/hr (100 mph)
• Steam is used to drive a turbo-generator
• Steam is condensed and pumped back into the
  ground
• Can achieve 1 kWh per 6.5 kg of steam
• A 55 MW plant requires 100 kg/s of steam

Boyle, Renewable Energy, 2nd edition, 2004
20
Dry Steam Schematic
Boyle, Renewable Energy, 2nd edition, 2004
21
Single Flash Steam Power Plants

• Steam with water extracted from ground
• Pressure of mixture drops at surface and more
  water flashes to steam
• Steam separated from water
• Steam drives a turbine
• Turbine drives an electric generator
• Generate between 5 and 100 MW
• Use 6 to 9 tonnes of steam per hour

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Single Flash Steam Schematic
Boyle, Renewable Energy, 2nd edition, 2004
23
Binary Cycle Power Plants

• Low temps 100o and 150oC
• Use heat to vaporize organic liquid
• E.g., iso-butane, iso-pentane
• Use vapor to drive turbine
• Causes vapor to condense
• Recycle continuously
• Typically 7 to 12 efficient
• 0.1 40 MW units common

http//www.worldenergy.org/wec-geis/publications/r
eports/ser/geo/geo.asp
24
Binary Cycle Schematic
Boyle, Renewable Energy, 2nd edition, 2004
25
Binary Plant Power Output
http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
26
Double Flash Power Plants

• Similar to single flash operation
• Unflashed liquid flows to low-pressure tank
  flashes to steam
• Steam drives a second-stage turbine
• Also uses exhaust from first turbine
• Increases output 20-25 for 5 increase in plant
  costs

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Double Flash Schematic
Boyle, Renewable Energy, 2nd edition, 2004
28
Combined Cycle Plants

• Combination of conventional steam turbine
  technology and binary cycle technology
• Steam drives primary turbine
• Remaining heat used to create organic vapor
• Organic vapor drives a second turbine
• Plant sizes ranging between 10 to 100 MW
• Significantly greater efficiencies
• Higher overall utilization
• Extract more power (heat) from geothermal resource

http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
29
Hot Dry Rock Technology

• Wells drilled 3-6 km into crust
• Hot crystalline rock formations
• Water pumped into formations
• Water flows through natural fissures picking up
  heat
• Hot water/steam returns to surface
• Steam used to generate power

http//www.ees4.lanl.gov/hdr/
30
Hot Dry Rock Technology
Fenton Hill plant
http//www.ees4.lanl.gov/hdr/
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Soultz Hot Fractured Rock
Boyle, Renewable Energy, 2nd edition, 2004
32
2-Well HDR System Parameters

• 2106 m2 2 km2
• 2108 m3 0.2 km3

Boyle, Renewable Energy, 2nd edition, 2004
33
Promise of HDR

• 1 km3 of hot rock has the energy content of
  70,000 tonnes of coal
• If cooled by 1 ºC
• Upper 10 km of crust in US has 600,000 times
  annual US energy (USGS)
• Between 19-138 GW power available at existing
  hydrothermal sites
• Using enhanced technology

Boyle, Renewable Energy, 2nd edition, 2004
34
Direct Use Technologies

• Geothermal heat is used directly rather than for
  power generation
• Extract heat from low temperature geothermal
  resources
• lt 150 oC or 300 oF.
• Applications sited near source (lt10 km)

http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
35
Geothermal Heat Pump
http//www.worldenergy.org/wec-geis/publications/r
eports/ser/geo/geo.asp
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Heat vs. Depth Profile
Boyle, Renewable Energy, 2nd edition, 2004
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Geothermal District Heating
Southhampton geothermal district heating system
technology schematic
Boyle, Renewable Energy, 2nd edition, 2004
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Direct Heating Example
Boyle, Renewable Energy, 2nd edition, 2004
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Technological Issues

• Geothermal fluids can be corrosive
• Contain gases such as hydrogen sulphide
• Corrosion, scaling
• Requires careful selection of materials and
  diligent operating procedures
• Typical capacity factors of 85-95

http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
40
Technology vs. Temperature
http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
41
Geothermal Performance
Boyle, Renewable Energy, 2nd edition, 2004
42
Environmental Implications
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Environmental Impacts

• Land
• Vegetation loss
• Soil erosion
• Landslides
• Air
• Slight air heating
• Local fogging
• Ground
• Reservoir cooling
• Seismicity (tremors)

• Water
• Watershed impact
• Damming streams
• Hydrothermal eruptions
• Lower water table
• Subsidence
• Noise
• Benign overall

http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
44
Renewable?

• Heat depleted as ground cools
• Not steady-state
• Earths core does not replenish heat to crust
  quickly enough
• Example
• Iceland's geothermal energy could provide 1700 MW
  for over 100 years, compared to the current
  production of 140 MW

http//en.wikipedia.org/wiki/Geothermal
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Economics of Geothermal
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Cost Factors

• Temperature and depth of resource
• Type of resource (steam, liquid, mix)
• Available volume of resource
• Chemistry of resource
• Permeability of rock formations
• Size and technology of plant
• Infrastructure (roads, transmission lines)

http//www.worldbank.org/html/fpd/energy/geotherma
l/cost_factor.htm
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Costs of Geothermal Energy

• Costs highly variable by site
• Dependent on many cost factors
• High exploration costs
• High initial capital, low operating costs
• Fuel is free
• Significant exploration operating risk
• Adds to overall capital costs
• Risk premium

http//www.worldbank.org/html/fpd/energy/geotherma
l/
48
Risk Assessment
http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
49
Geothermal Development
http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
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Cost of Water Steam
Table Geothermal Steam and Hot Water Supply Cost
where drilling is required
http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
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Cost of Geothermal Power
http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
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Direct Capital Costs
Direct Capital Costs (US /kW installed capacity)
http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
53
Indirect Costs

• Availability of skilled labor
• Infrastructure and access
• Political stability
• Indirect Costs
• Good 5-10 of direct costs
• Fair 10-30 of direct costs
• Poor 30-60 of direct costs

http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
54
Operating/Maintenance Costs
Operating and Maintenance Costs
http//www.worldbank.org/html/fpd/energy/geotherma
l/assessment.htm
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Geothermal Installations

• Examples

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Geothermal Power Examples
Boyle, Renewable Energy, 2nd edition, 2004
57
Geothermal Power Generation

• World production of 8 GW
• 2.7 GW in US
• The Geyers (US) is worlds largest site
• Produces 2 GW
• Other attractive sites
• Rift region of Kenya, Iceland, Italy, France, New
  Zealand, Mexico, Nicaragua, Russia, Phillippines,
  Indonesia, Japan

http//en.wikipedia.org/wiki/Geothermal
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Geothermal Energy Plant
Geothermal energy plant in Iceland
http//www.wateryear2003.org/en/
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Geothermal Well Testing
Geothermal well testing, Zunil, Guatemala     
http//www.geothermex.com/es_resen.html
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Heber Geothermal Power Station
52kW electrical generating capacity
http//www.ece.umr.edu/links/power/geotherm1.htm
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Geysers Geothermal Plant
The Geysers is the largest producer of geothermal
power in the world.
http//www.ece.umr.edu/links/power/geotherm1.htm
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Geyers Cost Effectiveness
Boyle, Renewable Energy, 2nd edition, 2004
63
Geothermal Summary
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Geothermal Prospects

• Environmentally very attractive
• Attractive energy source in right locations
• Likely to remain an adjunct to other larger
  energy sources
• Part of a portfolio of energy technologies
• Exploration risks and up-front capital costs
  remain a barrier

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Next Week BIOENERGY
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Supplementary Slides

• Extras

67
Geothermal Gradient
http//www.earthsci.org/mineral/energy/geother/geo
ther.htm
68
Geo/Hydrothermal Systems
http//www.freeenergynews.com/Directory/Geothermal
/
69
Location of Resources
http//www.worldenergy.org/wec-geis/publications/r
eports/ser/geo/geo.asp
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Ground Structures
Boyle, Renewable Energy, 2nd edition, 2004
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Volcanic Geothermal System
Boyle, Renewable Energy, 2nd edition, 2004
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Temperature Gradients
Boyle, Renewable Energy, 2nd edition, 2004
73
http//www.earthsci.org/mineral/energy/geother/geo
ther.htm
74
UK Geothermal Resources
Boyle, Renewable Energy, 2nd edition, 2004
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Porosity vs. Hydraulic Conductivity
Boyle, Renewable Energy, 2nd edition, 2004
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Performance vs. Rock Type
Boyle, Renewable Energy, 2nd edition, 2004
77
Deep Well Characteristics
Boyle, Renewable Energy, 2nd edition, 2004
78
Single Flash Plant Schematic
http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
79
http//www.worldbank.org/html/fpd/energy/geotherma
l/technology.htm
80
Binary Cycle Power Plant
http//www.worldenergy.org/wec-geis/publications/r
eports/ser/geo/geo.asp
81
Flash Steam Power Plant
http//www.worldenergy.org/wec-geis/publications/r
eports/ser/geo/geo.asp
82
Efficiency of Heat Pumps
Boyle, Renewable Energy, 2nd edition, 2004
83
Recent Developments

• Comparing statistical data for end-1996 (SER
  1998) and the present Survey, it can be seen that
  there has been an increase in world geothermal
  power plant capacity (9) and utilisation (23)
  while direct heat systems show a 56 additional
  capacity, coupled with a somewhat lower rate of
  increase in their use (32).
• Geothermal power generation growth is continuing,
  but at a lower pace than in the previous decade,
  while direct heat uses show a strong increase
  compared to the past.
• Going into some detail, the six countries with
  the largest electric power capacity are USA with
  2 228 MWe is first, followed by Philippines (1
  863 MWe) four countries (Mexico, Italy,
  Indonesia, Japan) had capacity (at end-1999) in
  the range of 550-750 MWe each. These six
  countries represent 86 of the world capacity and
  about the same percentage of the world output,
  amounting to around 45 000 GWhe.
• The strong decline in the USA in recent years,
  due to overexploitation of the giant Geysers
  steam field, has been partly compensated by
  important additions to capacity in several
  countries Indonesia, Philippines, Italy, New
  Zealand, Iceland, Mexico, Costa Rica, El
  Salvador. Newcomers in the electric power sector
  are Ethiopia (1998), Guatemala (1998) and Austria
  (2001). In total, 22 nations are generating
  geothermal electricity, in amounts sufficient to
  supply 15 million houses.
• Concerning direct heat uses, Table 12.1 shows
  that the three countries with the largest amount
  of installed power USA (5 366 MWt), China (2 814
  MWt) and Iceland (1 469 MWt) cover 58 of the
  world capacity, which has reached 16 649 MWt,
  enough to provide heat for over 3 million houses.
  Out of about 60 countries with direct heat
  plants, beside the three above-mentioned nations,
  Turkey, several European countries, Canada, Japan
  and New Zealand have sizeable capacity.
• With regard to direct use applications, a large
  increase in the number of GHP installations for
  space heating (presently estimated to exceed 500
  000) has put this category in first place in
  terms of global capacity and third in terms of
  output. Other geothermal space heating systems
  are second in capacity but first in output. Third
  in capacity (but second in output) are spa uses
  followed by greenhouse heating. Other
  applications include fish farm heating and
  industrial process heat. The outstanding rise in
  world direct use capacity since 1996 is due to
  the more than two-fold increase in North America
  and a 45 addition in Asia. Europe also has
  substantial direct uses but has remained fairly
  stable reductions in some countries being
  compensated by progress in others.
• Concerning RD, the HDR project at
  Soultz-sous-Forêts near the French-German border
  has progressed significantly. Besides the ongoing
  Hijiori site in Japan, another HDR test has just
  started in Switzerland (Otterbach near Basel).
• The total world use of geothermal power is giving
  a contribution both to energy saving (around 26
  million tons of oil per year) and to CO2 emission
  reduction (80 million tons/year if compared with
  equivalent oil-fuelled production).

http//www.worldenergy.org/wec-geis/publications/r
eports/ser/geo/geo.asp