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GEOTHERMAL ENERGY
* ABOUT THIS PRESENTATION
INTRODUCTION
SOURCES
OVERVIEW
16.5 BENEFITS & DISADVANTAGES
CONCLUSION
HISTRY
060306
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
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.
EARTH TEMPERATURE GRADIENT
http://www.geothermal.ch/eng/vision.html
Earth Temperature Gradient
EARTH DYNAMICS
http://www.worldbank.org/html/fpd/energy/geothermal/technology.htm
GEOTHERMAL IN CONTEXTEnergy 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
Nuclear Electric Power 7.862 8.033 8.143 7.959 8.232
Renewable Energy 6.158 5.328 5.835 6.082 6.117
Conventional Hydroelectric 2.811 2.242 2.689 2.825 2.725
Geothermal Energy 0.317 0.311 0.328 0.339 0.340
Biomassd 2.907 2.640 2.648 2.740 2.845
Solar Energy 0.066 0.065 0.064 0.064 0.063
Wind Energy 0.057 0.070 0.105 0.115 0.143
http://www.eia.doe.gov/cneaf/solar.renewables/page/geothermal/geothermal.html
U.S. Energy Consumption by Energy Source, 2000-2004 (Quadrillion Btu)
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.
ADVANTAGES OF GEOTHERMAL
http://www.earthsci.org/mineral/energy/geother/geother.htm
GEOTHERMAL SITE SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004
HOW GEOTHERMAL WORKS
Earth’s core heatWater → steam → drive electrical generatorsTurbinesArea specific• Geothermal energy is localized
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
GEOTHERMAL ENERGY: HISTORY
1926: a deep geothermal well was used to heat greenhouses.
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
* 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
080317
GEYSERS
http://en.wikipedia.org/wiki/Geyser
Clepsydra Geyser in Yellowstone
* 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
060320
Nearby Calistoga (started 1862) has tourist spas with hot water from springs;also palm reading, water treatments, psychics, mud baths, etc.
HOT SPRINGS
Hot springs in Steamboat Springs area.
GLOBAL GEOTHERMAL SITES
LOCATION OF RESOURCES
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
COST OF GEOTHERMAL POWER
Unit Cost(US ¢/kWh)
High Quality
Resource
Unit Cost (US ¢/kWh)
MediumQuality
Resource
Unit Cost (US ¢/kWh)
Low QualityResource
Small plants(<5 MW)
5.0-7.0 5.5-8.5 6.0-10.5
MediumPlants
(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
INDIRECT COSTS
Availability of skilled laborInfrastructure and accessPolitical stabilityIndirect 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
OPERATING/MAINTENANCE COSTSO&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
GENERATION OF ELECTRICITY
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
DRY STEAM SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004
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
SINGLE FLASH STEAM SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004
BINARY CYCLE POWER PLANTS
Low temps – 100o and 150oCUse heat to vaporize organic liquid• E.g., iso-butane, iso-pentane
Use vapor to drive turbine• Causes vapor to condense• Recycle continuouslyTypically 7 to 12 % efficient0.1 – 40 MW units common
http://www.worldenergy.org/wec-geis/publications/reports/ser/geo/geo.asp
BINARY CYCLE SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004
BINARY PLANT POWER OUTPUT
http://www.worldbank.org/html/fpd/energy/geothermal/technology.htm
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
DOUBLE FLASH SCHEMATIC
Boyle, Renewable Energy, 2nd edition, 2004
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
HOT DRY ROCK TECHNOLOGY
Wells drilled 3-6 km into crust• Hot crystalline rock formations
Water pumped into formationsWater flows through natural fissures picking up heatHot water/steam returns to surfaceSteam used to generate power
http://www.ees4.lanl.gov/hdr/
HOT DRY ROCK TECHNOLOGY
Fenton Hill plant http://www.ees4.lanl.gov/hdr/
2-WELL HDR SYSTEM PARAMETERS
• 2×106 m2 = 2 km2
• 2×108 m3 = 0.2 km3
Boyle, Renewable Energy, 2nd edition, 2004
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
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
GEOTHERMAL HEAT PUMP
http://www.worldenergy.org/wec-geis/publications/reports/ser/geo/geo.asp
HEAT VS. DEPTH PROFILE
Boyle, Renewable Energy, 2nd edition, 2004
GEOTHERMAL DISTRICT HEATING
Boyle, Renewable Energy, 2nd edition, 2004
Southhampton geothermal district heating system technology schematic
DIRECT HEATING EXAMPLE
Boyle, Renewable Energy, 2nd edition, 2004
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
TECHNOLOGY VS. TEMPERATUREReservoir
TemperatureReservoir
FluidCommon
UseTechnology
commonly chosenHigh Temperature
>220oC(>430oF).
Water orSteam
Power Generation
Direct Use• Flash Steam • Combined (Flash
and Binary) Cycle • Direct Fluid Use • Heat Exchangers • Heat Pumps
IntermediateTemperature
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
GEOTHERMAL PERFORMANCE
Boyle, Renewable Energy, 2nd edition, 2004
GEOTHERMAL ENERGY GENERATION
Direct
Small scale usesHeating homesHot springsGreenhouse heatingFood dehydration plants
Agriculture• Crop drying• Milk pasteurization
Electrical
Dry steamFlash steamBinary cycle
METHODS OF HEAT EXTRACTION
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
* 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
040322
Geothermal Installations
E X A M P L E S
GEOTHERMAL POWER EXAMPLES
Boyle, Renewable Energy, 2nd edition, 2004
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
GEOTHERMAL ENERGY PLANT
Geothermal energy plant in Icelandhttp://www.wateryear2003.org/en/
GEOTHERMAL WELL TESTING
http://www.geothermex.com/es_resen.html
Geothermal well testing, Zunil, Guatemala
HEBER GEOTHERMAL POWER STATION
http://www.ece.umr.edu/links/power/geotherm1.htm
52kW electrical generating capacity
GEYSERS GEOTHERMAL PLANTThe Geysers is the largest producer of geothermal power in the world.
http://www.ece.umr.edu/links/power/geotherm1.htm
GEYSER'S COST EFFECTIVENESS
Boyle, Renewable Energy, 2nd edition, 2004
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/enviroment.shtmlNorthern Arizona University. 2009 Oct 27)
ENVIRONMENTAL EFFECTS/BENEFITS
(http://www.geothermal.nau.edu/about/enviroment.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 1-8Nuclear 5-10Coal 19
RISK ASSESSMENT
http://www.worldbank.org/html/fpd/energy/geothermal/assessment.htm
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 stabilitySources may hold trace amounts of toxic chemicals/mineral deposits
Loud Noises
Initial start up cost (expensive)
(http://www.geothermal.nau.edu/about/enviroment.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
* 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
WHAT SOCIAL/POLITICAL PROBLEMS ARE POSED?
Social Problems• Aesthetics
Political Problems• Another funding
avenue for government• Initial start up cost is
costly• Regulation• Dispersion
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)
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
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
CONCLUSIONOverall, 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
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.
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
Puga Project (UNDP drilling)
PUGA PROJECTHimalayan Geothermal Province;
Located in extreme heat flow zone;
UNDP drill testing 1970’s.Geothermal waters @ >120°C @ 200m
75
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)
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);
76
• Current demand 59 MWe;• Regional support;• Attractive power tariffs;• No social/ environmental issues.
PUGA VALLEY IN SPRING (HIMALAYAN GEOTHERMAL PROVINCE)
• Negotiations with local Government in progress;• No environmental/social issues.
77
PUGA – GEOTHERMAL RESERVOIR AS DELINEATED BY MAGNETOTELLURIC SURVEYS (NGRI)
78Source: 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.
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.
79
Krishna-Godavari Basin and thermal/mineral spring location
ANDHRA PRADESH
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.
80