What is Geothermal Energy?

Answer

Literally "heat from the earth", but there are two ways to interpret that.

One is something like tapping into heat from magma reservoirs. This only occurs in limited places, but has the potential to generate a lot of energy, cheap.

The other is taking heat out of the ground (or putting it in) for heating. In my mind this is more properly called a "ground source heat pump" since there's not really any energy being generated.

Actually, geothermal energy can be generated in a large number of places. To get the heat from the earth, magma is not required. You simply need to drill down deep enough to find hot rocks (as opposed to molten rocks). This is quite deep (1-10 km). The heat is used to make electricity in the following way: cold water in injected into the drilled hole, and is then heated by the hot rocks below. The hot rocks produce steam, and that steam is used to turn a turbine (on the surface). The spinning turbine produces electricity.

The advantage of geothermal energy is that it does not produce carbon dioxide emissions. The disadvantage is that it requires very deep drilling (except in a few locations), which is not cheap. Another disadvantage is that the power plants can be noisy, creating noise pollution. Noise pollution is damaging to surroung wildlife. Also, the rocks below the surface are cooled by the water faster than they are re-heated, and so after 5-10 years of use, the site is no longer usable because the rocks are cold. Because of this limited lifetime, and the cost of drilling, geothermal isn't an ideal energy source.

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In simpler terms, Geothermal energy would be: Energy that is generated by converting hot water or steam from deep beneath the Earth's surface into electricity

First answer by Pgr-fw. Last edit by Tombo H. Contributor trust: 32 [recommend contributor]. Question popularity: 57 [recommend question]