The deeper into the earth you go, the warmer it happens to get. The earth’s core can reach temperatures of 7,600 degrees Fahrenheit (4,204 degrees Celsius). This heat deep underground is known as geothermal energy, and is naturally contained in the earth’s crust. Harnessing this energy can be a great renewable alternative as it’s not restricted to the time of day or whether or not it’s windy outside.
How does it work?
Deep underground, pools of water heated by magma and the earth’s crust lie in pools known as geothermal reservoirs. Dry steam plants — the most common type of geothermal power — pipe hot steam from these underground reservoirs into wind turbines that rotate to generate electricity. The steam then cools, turns back into water, and is simply piped back into the earth to be reused again.
There are other methods as well. Flash steam power plants pull the hot water from the earth and dump it straight into a cooling chamber, instantly turning the water into steam for the turbines. Binary cycle power plants (binary meaning two) use two liquids instead of just water. The second liquid will typically have a lower melting point (often isobutene) and will be kept in a separate tank. The hot water from the earth will boil the second liquid into steam to power the turbines in a sealed system.
How else can we use geothermal energy?
When reservoirs are near the earth’s surface we can use the heat to actually heat up our homes and offices in the winter. This is known as Direct Geothermal Energy.
Even the earth just a few feet beneath the ground can be used to warm and cool homes. In the winter we can channel water just a few feet underground and use electric compressors and heat exchangers to pull the heat from the pipes and into the building, this is known as a Geothermal Heat Pump. In the summer the process can be reversed and the pipes above ground draw in heat and can take the warmth underground to be absorbed.
How Does It Compare To Other Sources?
The initial cost of geothermal energy is high. But unlike other sources, it can be used 24/7 and the water is returned to the earth to be reheated and reused. So it is potentially the most consistent and least wasteful of any other energy source. As more advanced mining techniques are invented we may see geothermal energy become a major source for energy in the near future.