Geothermal energy is heat from within the Earth that can be used to generate electricity. It is extracted from hot water or steam underground. The heat comes from radioactive decay and residual heat from the Earth's formation. Some areas have naturally occurring hot springs or geysers that provide easy access to the geothermal heat. Electricity can be produced in facilities using dry steam, flash steam, binary cycle power plants, or other technologies. Geothermal energy has benefits like being renewable and having less environmental impact than fossil fuels, but also has some disadvantages like high initial costs and possible ground stability or noise issues.

2. * ABOUT THIS PRESENTATION
INTRODUCTION
SOURCES
OVERVIEW
16.5 BENEFITS &
DISADVANTAGES
CONCLUSION
HISTRY
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3. GEOTHERMAL ENERGY:
INTRODUCTION
What is geothermal energy?
Geothermal energy- energy that
comes from the ground; power
extracted from heat stored in the earth
• Geo: earth
• Thermal: heat

4. Heat flows outward from Earth's interior. The crust insulates us from
Earth's interior heat. The mantle is semi-molten, the outer core is liquid and
the inner core is solid.

5. EARTH TEMPERATURE GRADIENT
http://www.geothermal.ch/eng/vision.html
Earth Temperature Gradient

6. EARTH DYNAMICS
http://www.worldbank.org/html/fpd/energy/geothermal/technology.htm

7. GEOTHERMAL IN CONTEXT
Energy Source 2000 2001 2002 2003 2004P
Total a 98.961 96.464 97.952 98.714 100.278
Fossil Fuels 84.965 83.176 84.070 84.889 86.186
Coal 22.580 21.952 21.980 22.713 22.918
Coal Coke Net Imports 0.065 0.029 0.061 0.051 0.138
Natural Gasb 23.916 22.861 23.628 23.069 23.000
Petroleumc 38.404 38.333 38.401 39.047 40.130
Electricity Net Imports 0.115 0.075 0.078 0.022 0.039
http://www.eia.doe.gov/cneaf/solar.renewables/page/geothermal/geothermal.html
U.S. Energy Consumption by Energy Source, 2000-2004
(Quadrillion Btu)

8. HEAT FROM THE EARTH’S
CENTER
Earth's core maintains temperatures in excess of 5000°C
• 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.

9. ADVANTAGES OF GEOTHERMAL
http://www.earthsci.org/mineral/energy/geother/geother.htm

10. GEOTHERMAL SITE SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004

11. HOW GEOTHERMAL WORKS
Earth’s core heat
Water → steam → drive electrical generators
Turbines
Area specific
• Geothermal energy is localized

12. GEOTHERMAL ENERGY:
HISTORY
Used for bathing in Paleolithic times
Ancient Romans used it as a central heating
system for bathing and heating homes and
floors
1892: America’s first district heating system
was put into place

14. GEOTHERMAL ENERGY: HISTORY
1926: a deep geothermal well was used to heat
greenhouses.

15. GEOTHERMAL ENERGY: HISTORY
1960: Pacific Gas and Electric has
first successful geothermal electric
power plant in US at The Geysers
• Turbine lasted more than 30 years

16. * OVERVIEW: GEOTHERMAL
Geothermal energy is present within the land and the sea
• Internal heat is from initial world accretion from gathering dust and compression of the earth
and from radioactive decay
This energy can be useful in heating and cooling of air and water, but is
somewhat costly to use
Active geyser areas are limited in area, but provide much hotter water or
steam
The energy is inexhaustible in principle, yet local extraction will cool the
immediate area in a few years
Extraction of energy from deep (~20,000 ft) hot rock is not economic yet
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17. GEYSERS
http://en.wikipedia.org/wiki/Geyser
Clepsydra Geyser in Yellowstone

18. * GEOTHERMAL ENERGY
Active geysers supply steam or
hot water for heating in The
Geysers, California (824 MWe)
“Hot, dry rock” (HDR) offers
potential for injecting water and
using the resultant steam to spin a
turbine
At a lower thermal level, an air
conditioner can extract heat from
the ground for winter heating or
insert energy into the ground to
gain a more efficient cooling sink
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Nearby Calistoga (started 1862) has
tourist spas with hot water from
springs;
also palm reading, water treatments,
psychics, mud baths, etc.

19. HOT SPRINGS
Hot springs in Steamboat Springs area.

21. GLOBAL GEOTHERMAL SITES

22. LOCATION OF RESOURCES

23. COST OF WATER & STEAM
Cost
(US $/ tonne
of steam)
Cost
(US ¢/tonne
of hot water)
High temperature
(>150oC)
3.5-6.0
Medium
Temperature
(100-150oC)
3.0-4.5 20-40
Low Temperature
(<100oC)
10-20
Table Geothermal Steam and Hot Water Supply Cost where drilling is required

24. COST OF GEOTHERMAL POWER
Unit Cost
(US ¢/kWh)
High
Quality
Resource
Unit Cost
(US ¢/kWh)
Medium
Quality
Resource
Unit Cost
(US ¢/kWh)
Low Quality
Resource
Small plants
(<5 MW)
5.0-7.0 5.5-8.5 6.0-10.5
Medium
Plants
(5-30 MW)
4.0-6.0 4.5-7 Normally not
suitable
Large Plants
(>30 MW)
2.5-5.0 4.0-6.0 Normally not
suitable
http://www.worldbank.org/html/fpd/energy/geothermal/assessment.htm

25. 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/geothermal/assessment.htm

26. OPERATING/MAINTENANCE COSTS
O&M Cost (US
c/KWh)
Small plants
(<5 MW)
O&M Cost (US
c/KWh)
Medium Plants
(5-30 MW)
O&M Cost (US
c/KWh)
Large
Plants(>30
MW)
Steam field 0.35-0.7 0.25-0.35 0.15-0.25
Power Plant 0.45-0.7 0.35-0.45 0.25-0.45
Total 0.8-1.4 0.6-0.8 0.4-0.7
Operating and Maintenance Costs
http://www.worldbank.org/html/fpd/energy/geothermal/assessment.htm

27. GENERATION OF
ELECTRICITY

28. 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

29. DRY STEAM SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004

30. 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

31. SINGLE FLASH STEAM SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004

32. 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/reports/ser/geo/geo.asp

33. BINARY CYCLE SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004

34. BINARY PLANT POWER OUTPUT
http://www.worldbank.org/html/fpd/energy/geothermal/technology.htm

35. 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

36. DOUBLE FLASH SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004

37. 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/geothermal/technology.htm

38. 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/

39. HOT DRY ROCK TECHNOLOGY
Fenton Hill plant
http://www.ees4.lanl.gov/hdr/

40. 2-WELL HDR SYSTEM PARAMETERS
• 2×106 m2 = 2 km2
• 2×108 m3 = 0.2 km3
Boyle, Renewable Energy, 2nd edition, 2004

41. PROMISE OF HDR
1 km3 of hot rock has the energy content of
70,000 tones 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

42. DIRECT USE TECHNOLOGIES
Geothermal heat is used directly rather than
for power generation
Extract heat from low temperature
geothermal resources
• < 150 oC or 300 oF.
Applications sited near source (<10 km)
http://www.worldbank.org/html/fpd/energy/geothermal/technology.htm

43. GEOTHERMAL HEAT PUMP
http://www.worldenergy.org/wec-geis/publications/reports/ser/geo/geo.asp

44. HEAT VS. DEPTH PROFILE
Boyle, Renewable Energy, 2nd edition, 2004

45. GEOTHERMAL DISTRICT HEATING
Boyle, Renewable Energy, 2nd edition, 2004
Southhampton geothermal district heating system technology schematic

46. DIRECT HEATING EXAMPLE
Boyle, Renewable Energy, 2nd edition, 2004

47. 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/geothermal/technology.htm

48. TECHNOLOGY VS. TEMPERATURE
Reservoir
Temperature
Reservoir
Fluid
Common
Use
Technology
commonly chosen
High Temperature
>220oC
(>430oF).
Water or
Steam
Power Generation
Direct Use
• Flash Steam
• Combined (Flash
and Binary) Cycle
• Direct Fluid Use
• Heat Exchangers
• Heat Pumps
Intermediate
Temperature
100-220oC
(212 - 390oF).
Water Power Generation
Direct Use • Binary Cycle
• Direct Fluid Use
• Heat Exchangers
• Heat Pumps
Low Temperature
50-150oC
(120-300oF).
Water Direct Use
• Direct Fluid Use
• Heat Exchangers
http://www.worldbank.org/html/fpd/energy/geothermal/technology.htm

49. GEOTHERMAL PERFORMANCE
Boyle, Renewable Energy, 2nd edition, 2004

50. GEOTHERMAL ENERGY
GENERATION
Direct
Small scale uses
Heating homes
Hot springs
Greenhouse heating
Food dehydration plants
Agriculture
• Crop drying
• Milk pasteurization
Electrical
Dry steam
Flash steam
Binary cycle

51. METHODS OF HEAT EXTRACTION

52. CAN GEOTHERMAL ENERGY RUN OUT?
100% renewable
• Earth’s core is always going to be heated
• As long as there is a way to extract the
energy from the heat, the energy will
always be available

53. * SOURCE OF GEOTHERMAL ENERGY
Heat stems from radioactive
disintegrations of atomic nuclei
[Sorensen, 2000], initial cooling
from agglomeration in planet
formation, and other various
processes
Hot spots occur where strong
convective magma circulation is
occurring, usually near
continental plate boundaries and
mountainous regions
Hot dry rock, the most common
type, retains convective heat
Storage in a developed area
may be depleted in 50 years
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54. Geothermal Installations
E X A M P L E S

55. GEOTHERMAL POWER EXAMPLES
Boyle, Renewable Energy, 2nd edition, 2004

56. GEOTHERMAL POWER GENERATION
World production of 8 GW
• 2.7 GW in US
The Geyers (US) is world’s 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

57. GEOTHERMAL ENERGY PLANT
Geothermal energy plant in Iceland
http://www.wateryear2003.org/en/

58. GEOTHERMAL WELL TESTING
http://www.geothermex.com/es_resen.html
Geothermal well
testing, Zunil,
Guatemala

59. HEBER GEOTHERMAL POWER
STATION
http://www.ece.umr.edu/links/power/geotherm1.htm
52kW electrical generating capacity

60. GEYSERS GEOTHERMAL PLANT
The Geysers is the largest producer of
geothermal power in the world.
http://www.ece.umr.edu/links/power/geotherm1.htm

61. GEYSER'S COST EFFECTIVENESS
Boyle, Renewable Energy, 2nd edition, 2004

62. ENVIRONMENTAL EFFECTS/
BENEFITS
Remarkable difference
of environmental
effects compared to
fossil fuels
• Leaves almost no footprints
Most hardware used to
extract geothermal
energy is underground
• Minimal use of surface
(http://www.geothermal.nau.edu/about/enviro
ment.shtmlNorthern Arizona University.
2009 Oct 27)

63. ENVIRONMENTAL
EFFECTS/BENEFITS
(http://www.geothermal.nau.edu/about/env
iroment.shtml> Northern Arizona
University. 2009 Oct 27)
Easy to operate
Open up economy
Much more
efficient use of land
Power Source Land
Requirement
(ac/mW)
Geothermal 1-8
Nuclear 5-10
Coal 19

64. RISK ASSESSMENT
http://www.worldbank.org/html/fpd/energy/geothermal/assessment.htm

65. ENVIRONMENTAL EFFECTS/
DISADVANTAGES
Fluids drawn from the deep earth
carry a mixture of gases
Pollutants contribute to global
warming and acid rain
Construction of Plants can
adversely affect land stability
Sources may hold trace amounts of
toxic chemicals/mineral deposits
Loud Noises
Initial start up cost (expensive)
(http://www.geothermal.nau.edu/about/envirome
nt.shtml> Northern Arizona University. 2009
Oct 27)
Operation Noise Level (dBa)
Air drilling 85–120
Mud drilling 80
Discharging wells after drilling (to
remove drilling debris)
Up to 120
Well testing 70–110
Diesel engines (to operate
compressors and provide
electricity)
45–55
Heavy machinery (e.g., for earth
moving during construction)
Up to 90

66. * MAMMOTH PACIFIC POWER PLANT, CA
“Located in the eastern Sierra Nevada mountain range in California, showcases the
environmentally friendly nature of geothermal power.” ---- ASES policy, 2005

67. WHAT SOCIAL/POLITICAL
PROBLEMS ARE POSED?
Social Problems
• Aesthetics
Political Problems
• Another funding
avenue for
government
• Initial start up cost is
costly
• Regulation
• Dispersion

68. DO ANY LAWS OR REGULATIONS
PREVENT THE DEPLOYMENT OF
GEOTHERMAL ENERGY?
Depends on state and specific
community: not any federal laws
Factors to consider
• Noise
• Aesthetics
• Proximity to houses
• Waste regulation (some use coolants)

69. WHAT EVIDENCE SUPPORTS
GEOTHERMAL?
New facilities produce electricity for $.045/kW hour
Price is declining compared to price of fossil fuels,
which is increasing
The US can produce and 950,000 megawatts of power
but are currently only producing 2,800 megawatts of
power
• This number is going to constantly increase with new technologies
and research

70. 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

71. CONCLUSION
Overall, geothermal appears to be a sound solution to energy needs
Geothermal energy has the ability to expand
Few environmental effects
Very cost efficient
Geothermal is RENEWABLE

72. Indian Energy Sector – Geothermal Energy
Indian Geothermal
provinces can produce up
to 10600 MW of power.
Government has identified
340 hot springs in the
country and are planning
to develop some of the
Geothermal fields for
power generation.

73. Indian Energy Sector – Geothermal Energy
International consultant, GeothermEx Inc., USA has identified
has identified 6 most promising Geothermal sites for
development in order of the following ranking:
• Tattapani in Chhatisgarh
• Puga in Jammu & Kashmir
• Cambay Graben in Gujarat
• Manikaran in Himachal Pradesh
• Surajkund in Jharkhand
• Chhumanthang in Jammu & Kashmir
National Hydro Power Corporation (NHPC) has been appointed
by the government as the nodal agency to promote geothermal
energy in India. NHPC plans to develop 2 to 5 MW geothermal
power plant at Puga.
Chhatisgarh Renewable Energy Development Agency (CREDA)
is currently developing the Tattapani geothermal site.

74. 73
Puga Project (UNDP drilling)
PUGA PROJECT
Himalayan Geothermal Province;
Located in extreme heat flow zone;
UNDP drill testing 1970’s.
Geothermal waters @ >120°C @ 200m

75. 74
PUGA PROJECT - HIMALAYAN
GEOTHERMAL PROVINCE
Earning up to 49% in Puga project
(A$6M);
Known geo-pressured geothermal
wells (UNDP – 1970’s);
Extreme geothermal gradients (e.g.
1.2km 250oC);
Analogue to Yangbajing geothermal
province in Tibet (35 MWe);
Ready for drill testing (low risk);
Potential World Bank support, PRI;
Commercially attractive power tariffs
plus CDM.
Geopressured well, Puga Valley India
(geothermal waters are at boiling temperature
which is equivalent to 87°C at this high
altitude)

76. INDIA: PUGA PROJECT – LOCATION
MAP
Puga – Leh = distance of 140km;
Leh – ‘tourist’ capital of Indian Himalaya’s;
Leh relies on diesel generation (13 MWe) and small scale hydro (2 MWe);
75
• Current demand 59 MWe;
• Regional support;
• Attractive power tariffs;
• No social/ environmental issues.

77. PUGA VALLEY IN SPRING
(HIMALAYAN GEOTHERMAL PROVINCE)
• Negotiations with local Government in progress;
• No environmental/social issues.
76

78. PUGA – GEOTHERMAL RESERVOIR AS
DELINEATED BY MAGNETOTELLURIC
SURVEYS (NGRI)
77
Source: GeoSyndicate Power Private Limited
3-D view of top surface of deeper
conductor showing presence of
geothermal reservoir;
High temperature geothermal
reservoir (>260°C) at 2,000m.

79. KRISHNA-GODAVARI BASIN
High heat flow region (rift valley);
‘Wet’ geothermal targets;
13 thermal springs recorded;
Temperature: 170 - 215°C @ approx 2,500m;
Previous studies indicated potential for 38
MWe power plant;
Good infrastructure;
Power shortages, lack of clean power.
78
Krishna-Godavari Basin and
thermal/mineral spring location
ANDHRA PRADESH

80. KYRGYZ REPUBLIC – CENTRAL ASIA
JV with Kentor Gold Limited (ASX: KGL), earning up to 61% in six
geothermal licences; JV extends to other counties C. Asia;
Extreme high heat flows and geothermal gradients;
High quality soviet era database;
Widespread occurrence of thermal springs;
Government support – World Bank interest;
Extensive transmission grid, regional power shortages, net
exporter of power;
Connected to Eurasian rail network.
79