What is Geothermal Energy?

Geothermal energy is generated and stored in the Earth. The source of the energy comes from the radioactive decay of materials in the Earth’s crust.  Power plants can use this geothermal heat to produce steam and spin turbines to generate power.

Most commercial geothermal power plants tap into subterranean reservoirs of water that is heated from geothermal sources. Since the water reservoirs are pressurized, the water does not boil even though the temperature usually ranges from 125 degrees Celsius to 225 degrees Celsius. Here is what a commercial geothermal plant looks like.


Here are some quick facts regarding geothermal energy:

  • For every 100m you go below ground, the temperature increases about 3 degrees Celsius.
  • Over 26% of Iceland’s electricity comes from geothermal energy.
  • Geothermal is considered a renewable energy source since the water reservoirs are replenished by rain and continuously heated by the Earth.

Geothermal power doesn’t always have to involve steam and large commercial plants. There are geothermal heat pump systems that can be installed for individual houses. These systems utilize the constant ground temperature as either a heat sink or heat source depending on whether the house requires heating or cooling. Below is an image of what a residential geothermal loop system looks like. The loops allow the geothermal heat pumps to extract or inject heat into the ground as needed.


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