Geothermal energy is a renewable source of energy that can be used in both residential and commercial heating and cooling and large-scale power generation applications. Both systems rely on using heat energy that comes from below the earth’s surface, but residential or commercial heating uses low-temperature earth energy in a GeoExchange Heating/Cooling process, while large-scale power generation uses medium- to high-temperature earth energy.
The idea behind GeoExchange heating and cooling is to take advantage of the ground’s heating and cooling properties that make our basements cooler in the summer and warmer in the winter. About 1.5 metres below the surface, the ground temperature remains fairly constant, around approximately 55 to 65 degrees. GeoExchange uses this constant temperature to provide heating or cooling for residential and commercial spaces.
Closed-loop systems are the most common systems and involve installing piping coming from the home into drilled boreholes that go down into the ground and return back to the home. An environmentally friendly liquid solution is pumped through the piping, which absorbs energy from the earth’s surface. The system also uses a heat pump unit as well as a compressor.
Heat pumps extract heat from one source and transfer it to another; in the winter, the heat pump takes the heat from the earth’s surface and transfers it into the home or building, heating the space, while in the summer, heat is absorbed from the air in the home and transferred into the fluid to be released below ground. The compressors are used to move the fluid through the pipes. The only external energy required is to operate the heat pump system and compressor.
Geothermal energy is heat energy that comes from below the earth’s surface. We live on the earth’s surface, or crust, but below us, in the centre of the earth, is a molten-hot core. This core radiates heat out towards the surface and can heat outer rocks in the mantle layer, producing magma, or liquid rock. Sometimes, water can be heated from this magma, creating geothermal reserves, or hot springs.
One way of using this stored energy is by drilling into the ground to allow heated water and steam to rise to the surface. The steam can be captured and used to drive turbines, which produce electricity. These generating stations often use a closed-loop system of bringing water to the surface and returning it for re-heating after it has cooled.
These types of power plants generally require very high temperature reservoirs, which are mostly limited to areas near volcanoes and tectonic plate boundaries, where the heat energy is located close to the surface.
The benefits of geothermal energy include:
* Geothermal energy sources are a clean source of generating energy; they do not use combustion to generate energy and produce no greenhouse gas emissions.
* Geothermal energy is a renewable resource.
* Geothermal systems require minimal surface land for operation compared to other power generating sources.
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