Uses of geothermal power
Three main types of geothermal energy systems include:
- Binary cycle power plants transfer the heat from geothermal hot water to another liquid. The heat causes the second liquid to turn into steam, which is then used to drive a generator turbine.
- Dry steam plants use steam transferred directly from a geothermal reservoir to move generator turbines.
- Flash steam plants convert high-pressure hot water into steam, which drives generator turbines. When the steam cools, it condenses to water and is then injected back into the ground to be used again. Most geothermal power plants are flash steam plants.
The United States is first in the world in electricity generated by geothermal energy. According to the U.S. Energy Information Administration (EIA), in 2013, geothermal power plants in created 17 billion kilowatt hours (kWh), or 0.4 percent of total electricity generation nationwide. As of 2013, six states had geothermal power plants.
Most of the geothermal power plants in the United States are located in the Western states and in Hawaii, where geothermal energy resources are close to the earth's surface. California generates the most electricity from geothermal energy. The Geysers dry steam reservoir in northern California is the largest known dry steam field in the world and has been producing electricity since 1960.