geothermal energy.ppt

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Geothermal Energy?

Heat from within the earth.

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Tectonic Plate Movements

Boyle, Renewable Energy, 2nd edition, 2004

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Global Geothermal Sites

http://www.deutsches-museum.de/ausstell/dauer/umwelt/img/geothe.jpg

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Earth

l

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GeothermalGeothermal

Greek word

Geo = earth Therme = heat

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Resources of Geothermal Energy

Hydro-thermal Petro-thermal Geopressure

Magma ResourcesVal canoes

Dry-steam Wet-steamHot-Water Fields

Hot dry rocksPorous rocks

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Advantages of Geothermal

http://www.earthsci.org/mineral/energy/geother/geother.htm

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Power –Plant System

There are three designs for geothermal power plants, all of which pull hot water and steam from the ground, use it, and then return it as warm water to prolong the life of the heat source

Dry steam Power Plant Flash Steam Power Plant Binary Cycle Power Plant

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Dry Steam Plant

. In the simplest design, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water.

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Dry Steam Schematic


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Flash Steam Power Plant

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

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Flashed System

In a second approach, very hot water is depressurized or "flashed" into steam which can then be used to drive the turbine.

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Single Flash Steam Schematic


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Binary System

In the third approach, called a binary system, the hot water is passed through a heat exchanger, where it heats a second liquid—such as isobutane—in a closed loop. The isobutane boils at a lower temperature than water, so it is more easily converted into steam to run the turbine.

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Geysers

http://en.wikipedia.org/wiki/Geyser

Clepsydra Geyser in Yellowstone

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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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FumarolesClay Diablo Fumarole (CA) White Island Fumarole

New Zealand

http://volcano.und.edu/vwdocs/volc_images/img_white_island_fumerole.htmlhttp://lvo.wr.usgs.gov/cdf_main.htm

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Methods of Heat Extraction

http://www.geothermal.ch/eng/vision.html

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Binary Cycle Schematic


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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/

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Hot Dry Rock Technology

Fenton Hill plant http://www.ees4.lanl.gov/hdr/

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Technology vs. TemperatureReservoirTemperature

ReservoirFluid

CommonUse

Technologycommonly chosen

High 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

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Geothermal Performance


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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/geothermal/assessment.htm

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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/geothermal/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/geothermal/

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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

http://www.worldbank.org/html/fpd/energy/geothermal/

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Geothermal Development


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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

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Cost of Geothermal PowerUnit 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


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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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Application

Generation of electric power Industrial Process heat Food processing Space heating for building Bathing facilities

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Environmental Effects

Air pollution

emission of poisonous gases such as H2S,AMMONIA,METHANE,CARBON DIOXIDE etc.

Noise Pollution

Thermal Pollution

Land subsidence caused by fluid withdrawal

Dense fog on local atmosphere.

Radio-active material escaping

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Thank You!!!

geothermal energy.ppt

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