Clean Renewable Energy
How it Works
Geothermal energy is energy that is produced by harnessing the Earth's internal heat. This energy is contained in the rocks, molten rock and other fluids beneath the Earth's crust. It can be found both near the surface as well as very deep underground, it even reaches the point where there is extremely hot molten rock called magma.
These underground reservoirs of steam and hot water can be used to generate electricity or even to directly heat and cool buildings.
A geothermal heat pump can use the constant temperature of the upper 3 meters of the earth's surface to heat homes in the winter, but also to extract heat from the building and transfer it back into the cooler ground in summer.
Geothermal water found even deeper underground can be used directly for the heating of homes and offices; it can even be used to grow plants in greenhouses.
In order to gain access to and harness the geothermal energy wells have to be dug, some even reaching a depth of 1.6 kilometers deep or more, allowing access to the steam very hot sub-terminal water that is used to drive the turbines linked to electricity generators.
There are 3 different types of geothermal plant: dry steam, flash and binary. Dry steam is the oldest form of geothermal energy; it works by extracting steam from fractures in the ground and uses it to drive a turbine. The flash plants pull deep, high-pressure hot water into cooler, low-pressure water, this process produces steam which is then used to turn a turbine and therefore generate electricity. In binary plants the boiling hot water is passed very near another secondary fluid that has a much lower boiling point than the water does. This will cause the secondary liquid to turn into vapor, which will then be used to turn a turbine. Most geothermal plants of the future will be binary plants.
Geothermal energy is produced and used in over 20 countries all around the world. The United States is the largest producer in the world; it also has the world's largest geothermal development, The Geysers north of San Francisco in California. In Iceland hot geothermal water is used to heat buildings and even swimming pools. There are at least 25 active volcanoes, as well as many hot springs and geysers in Iceland.
There are many advantages of geothermal energy:
However it still offers some environmental risks. The main problem is the release of hydrogen sulfide. Another concern is the disposal of some geothermal fuels, which may contain low levels of toxic materials. Another problem is that even though geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down.
National Geographic Society (2008) Geothermal Energy Information ,Solar Power Energy Facts [Online] (Updated 2008)
Geoberg (2007) Geothermal Energy in Iceland [Online] (2 February 2009)
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