Geothermal

GEOTHERMAL ENERGY

* ABOUT THIS PRESENTATION

INTRODUCTION

SOURCES

OVERVIEW

16.5 BENEFITS & DISADVANTAGES

CONCLUSION

HISTRY

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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

http://geothermal.marin.org/video/vid_pt1.html

http://upload.wikimedia.org/wikipedia/commons/9/9f/NesjavellirPowerPlant_edit2.jpg

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


1926: a deep geothermal well was used to heat greenhouses.


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

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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

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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.

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


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


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


DRY STEAM SCHEMATIC


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


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


BINARY PLANT POWER OUTPUT


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


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


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


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


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)


GEOTHERMAL HEAT PUMP

http://www.worldenergy.org/wec-geis/publications/reports/ser/geo/geo.asp

HEAT VS. DEPTH PROFILE


GEOTHERMAL DISTRICT HEATING


Southhampton geothermal district heating system technology schematic

DIRECT HEATING EXAMPLE


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%


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


GEOTHERMAL PERFORMANCE


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

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Geothermal Installations

E X A M P L E S

GEOTHERMAL POWER EXAMPLES


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


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


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.

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Puga Project (UNDP drilling)

PUGA PROJECTHimalayan Geothermal Province;

Located in extreme heat flow zone;

UNDP drill testing 1970’s.Geothermal waters @ >120°C @ 200m

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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);

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• 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.

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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.

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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.

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