Geothermal energy is a type of renewable energy that is generated by harnessing the heat from the Earth's core. It is a clean and sustainable energy source that can be used to generate electricity and to provide heating and cooling. There are several different ways that geothermal energy can be harnessed, including the use of geothermal power plants and geothermal heat pumps.

Geothermal power plants generate electricity by tapping into underground reservoirs of hot water or steam. These reservoirs are typically found a few miles below the Earth's surface and are accessed through a well. The hot water or steam is brought to the surface and used to generate electricity in a similar way to how steam is used in a coal-fired power plant.

Diagram courtesy of US Environmental Protection Agency 

As seen above:

1. Hot water is pumped from the deep underground of the Earth’s hot interior through a well under high pressure.

2. When the water finally reaches the surface, the pressure is then dropped. This drop in pressure causes the hot water to be converted into steam.

3. The steam spins a turbine which is connected to a generator that produces electricity

4. The steam then cools off in a cooling tower and is condensed back into water form. 

5. The cooled water is then pumped back into the Earth to start the process again.

Benefits and Drawbacks

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