Geothermal Energy Prepared by: Parth H. Patel (120780119058)

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

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

Geothermal Energy: History Used for bathing in Paleolithic times Ancient Romans used it as central heating system for bathing and heating homes and floors 1892:America’s first district heating system was put into place

Power Plant in Larderello Today

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

How Geothermal Works Earth’s core heat Water → steam → drive electrical generators Turbines Area specific Geothermal energy is localized

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

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

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

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

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 Easy to operate Open up economy Much more efficient use of land

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)

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

(http://www. geothermal. nau. edu/about/enviroment (http://www.geothermal.nau.edu/about/enviroment. shtmlNorthern Arizona University. 2009 Oct 27)

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