Geothermal Facts
The Science of Geothermal
Geothermal Energy has been around for as long as the Earth has existed. “Geo” means earth, and “thermal” means heat. So, geothermal means earth-heat.
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The entire world resource base of geothermal energy has been calculated in government surveys to be larger than the resource bases of coal, oil, gas and uranium combined.
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For every 100 meters you go below ground, the temperature of the rock increases about 3 degrees Celsius. Or for every 328 feet below ground, the temperature increases 5.4 degrees Fahrenheit.
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The word geothermal comes from the Greek words geo (earth) and therme (heat). So, geothermal energy is heat from within the Earth. We can recover this heat as steam or hot water and use it to heat buildings or generate electricity.
Geothermal energy is a renewable energy source because the heat is continuously produced inside the Earth.
Source: US Energy Information Administration
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Geothermal energy is generated in the Earth’s core. Temperatures hotter than the sun’s surface are continuously produced inside the Earth by the slow decay of radioactive particles, a process that happens in all rocks. The Earth has a number of different layers… Learn more
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The environmental impact of geothermal energy depends on how it is being used. Direct use and heating applications have almost no negative impact on the environment… Learn more
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Geothermal Usage
Even though geothermal energy is technically a finite resource, the typical lifetime for geothermal activity around magmatic centers – from 5,000 years to 1,000,000 years – is so long that it is considered a renewable resource.
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About 10.000 years ago, Paleo-Indians used hot springs in North America for cooking. Areas around hot springs were neutral zones. Warriors of fighting tribes would bathe together in peace.
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About 2850 megawatts of geothermal generation capacity is available from power plants in the western United States. Geothermal energy generates about 2% of the electricity in Utah, 6% of the electricity in California and almost 10% of the electricity in northern Nevada.
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Most of the geothermal power plants in the United States are located in the western States and Hawaii, where geothermal energy resources are close to the 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… Learn more
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The United States leads the world in electricity generation with geothermal power. In 2009, U.S. geothermal power plants produced 15.2 billion kilowatt-hours, or 0.4% of total U.S. electricity generation. Seven States have geothermal power plants… Learn more
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There are three basic types of geothermal power plants:
- Dry steam plants use steam piped directly from a geothermal reservoir to turn the generator turbines. The first geothermal power plant was built in 1904 in Tuscany, Italy, where natural steam erupted from the Earth.
- Flash steam plants take high-pressure hot water from deep inside the Earth and convert it to steam to drive the generator turbines. When the steam cools, it condenses to water and is injected back into the ground to be used over and over again. Most geothermal power plants are flash steam plants.
- Binary cycle power plants transfer the heat from geothermal hot water to another liquid. The heat causes the second liquid to turn to steam which is used to drive a generator turbine… Learn more
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