WHAT IS & how does GEOTHERMAL ENERGY ?????
The Earth's heat called-Geothermal energy which -escapes as steam, is clean, and renewable.
The resources of geothermal energy range from the shallow pockets in the earths upper crust, to hot water and hot rock found a few miles beneath in the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.
In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii.
Almost everywhere,in the upper 10 feet of the Earth's surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C) . Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger (a system of pipes buried in the shallow ground near the building ). In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer,the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.

ADVANTAGES
advantage of using geothermal heat to power a power station is that, unlike most power stations, a geothermal system does not create any pollution. It may once in a while release some gases from deep down inside the earth, that may be slightly harmful, but these can be contained quite easily.
The cost of the land to build a geothermal power plant on, is on average usually less expensive than if you were planning to construct an; oil, gas, coal, or nuclear power plant on a patch of land. The main reason for this is less land is used becaus eof the relativly small size of geothermal power plants, so you don't need to purchase a larger area of land. also because geothermal energy is very clean there is a minimal amount of dangerous chemicals released when it is pump out

disadvantages
Locations
One of the biggest disadvantages of geothermal energy is the low number of suitable locations for a power plant. An ideal location has suitable hot rocks at a depth that allows for easy drilling. The type of rock above the hot rocks must also be easy enough to drill through. After finding a suitable location, there is another drawback. some other set back are LongevitySometimes the locations may temporarily run out of steam. During this time, the power plant won't have enough energy to generate electricity.another one is Transportation Oil is extremely easy to transport; but because geothermal energy is presuerized steam it cannot be esaely transported out of the serounding reagion One of the disadvantages of geothermal energy is that it is not easily transported. It can only be used to generate electricity for surrounding areas. Hazardous Materials One of the most common substances to be released when geothermal energy is pumped out is hydrogen sulfide, which is extremely difficult to dispose of safely. Other minerals that can be troublesome are arsenic, mercury, and ammonia.


referance links
http://www.associatedcontent.com/article/288108/five_disadvantages_of_geothermal_energy.html?cat=15
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http://www.clean-energy-ideas.com/articles/advantages_of_geothermal_energy.html
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http://www.renewableenergyworld.com/rea/tech/geothermal-energy