Geothermal energy is heat derived from the Earth. It is both clean and sustainable. It can be excavated from shallow ground, hot water, hot rocks, and magma. Geothermal energy can be extracted through power plants and heat pumps.

There are three types of geothermal power plants. The first type is called dry steam and uses heat from deep within the Earth to generate steam, which produces electricity. Wells drill into the Earth and pump hot water to the surface under high pressures. Once at the Earth’s surface, the pressure is decreased causing the water to turn into steam. The steam is spun in a turbine that is connected to a generator that produces electricity. As the steam cools off it converts back into water and is then pumped back into the Earth where the process begins again. The second type, known as a binary cycle power plant, sends hot water through a heat exchanger where it heats a second liquid (second liquid may vary). The second liquid boils at a lower temperature than water; therefore, it is easier to convert into steam to power the turbine. Binary cycle power plants emit little to no air emissions. The third type is known as flash steam. Flash steam power plants are the most common of the three. They use reservoirs of water with extremely high temperatures. The water is so hot that it is able to flow up to the surface of the earth under its own pressure. As it reaches the surface the pressure decreases and steam is produced. The steam is then used to power a turbine or generator. Surplus water and condensed steam are inserted back into the reservoir making this a sustainable resource.