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Geothermal Energy
Geothermal energy uses steam produced from reservoirs of hot water found miles below the earths surface, to drive a series of turbines to generate electricity. There are three main types of geothermal electricity creation. Dry steam sites pipe steam directly from their source underground through to the generator to generate the power. The second type of plant, called “Flash” plants utilise hot water found deep in the ground. As the water rises towards the surface the decreasing pressure causes some of the liquid to boil to steam. Once this occurs the steam is separated from the water and directed to a turbine to create electricity. The third and final method of geothermal electricity generation is called Binary. These sites draw the hot water from underground and then direct it to a location where it is used to boil a working fluid. This working fluid will have a low boiling point and the heat transfer from the hot water vaporises it as it is passed through a heat exchanger. The resulting vapour is then used to drive a turbine leading to electricity creation. During this process the rising water will cool naturally, and after it has been used to heat the organic compound it is then fed back to its original source where it is re-heated for reuse.
At present there are only a very small number of geothermal plants located around the world, none of which make significant contributions to renewable energy figures. There is however the potential for this method to be used in rural applications. A technology such as this is a relatively sustainable source of low level power but it is a costly method of power creation to implement. The sites would require drilling in order to reach the depth where the water is heated sufficiently to create steam, with the only alternative being to place the sites in locations where naturally occurring wells appear. The later is both impractical and cost deficient and for the level of power created not an economically viable solution.
Although the ground water everywhere in the world becomes heated at a certain depth it is unlikely that this method will ever be a true alternative to the other forms of renewable energy. In order to see a return on the investment of building such a plant would take a considerable length of time and although it may have a use in countries with large areas of desolation, such as Texas, it is an impractical solution for the UK.