Geothermal

Geo the Earth

Thermal Heat

Geothermal energy is the natural heat of the Earth. It is a renewable energy source for electricity generation

Why Geothermal?

• Our planet is a huge source of energy. In fact 99.9per cent of the planet is at a temperature greaterthan 100°C; so geothermal energy is a significantrenewable resource(c).

• Geothermal energy has the advantage that it canbe available 24/7 all year round providingconstant power with minimal visual andenvironmental impacts that other low carbonform of energy production cannot.

Geothermal reservoirs

• Geyser

• Boiling mud pot

• Volcano

• Hot springs

Energy Sourse used in 24 countries

Geothermal reservoirs can reach temperatures of 700oF.

History

• Prince Piero Ginori Conti tested the first geothermal powergenerator on 4 July 1904 in Larderello, Italy. It successfully lit fourlight bulbs.

• Later, in 1911, the world's first commercial geothermal power plantwas built there.

• Italy was the world's only industrial producer of geothermalelectricity until 1958.

• In 1958, New Zealand became the second major industrial producerof geothermal electricity.

• In 1960, Pacific Gas and Electric began operation of the firstsuccessful geothermal electric power plant in the United States atThe Geysers in California.

• The binary cycle power plant was first demonstrated in 1967 inRussia and later introduced to the USA in 1981.

• Worldwide, 11,400 megawatts (MW) of geothermal power is onlinein 24 countries in 2012.

Direct use of Geothermal Energy

• Hot springs, used as spas.

• Heating water at fish farms.

• Provide heat for buildings.

• Raising plants in greenhouses, drying crops.

• Provides heat to industrial processes.

Resources

• Electricity generation requires high temperature resources that can only come from deep underground.

• The heat must be carried to the surface by fluid circulation, either through: Magma conduits Hot springs Hydrothermal circulation Oil wells Drilled water wells or a combination of these.

• Away from tectonic plate boundaries the geothermal gradient is 25-30°C per km of depth in most of the world, and wells would have to be several kilometers deep to permit electricity generation.

• The quantity and quality of recoverable resources improves with drilling depth and proximity to tectonic plate boundaries

Dry Steam Plant

Flash Steam Plant

Binary Cycle Plants

Enhanced Geothermal Systems

Cost

Direct use of geothermal energy is absolutely cheaper than other energy sources. Cost of electricity generation depends upon certain factors:• Temperature and depth of resource • Type of resource (steam, liquid, mix) • Available volume of resource • Size and technology of plantThe initial investment is high. But after certain time period, the cost of electricity becomes comparable to other resources of energy. US $0.05 to $0.08 per kWh. Once the capital cost is recovered, the price can decrease to below US $0.05 per kWh.

Advantages

• Available all the year around

• Does not involve any combustion of fuel

• Independent of weather

• Clean Resource – Very little emissions oroverall environmental impact

• Economically Sound Alternative – The fuel isfree, rate / KWh likely to be competitive

Disadvantages

• Not widespread source of energy

• High installation costs

• Can run out of steam

• May release harmful gases

• Transportation

• Earthquakes