Geothermal energy
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Geothermal energy is created by using water or steam from geothermal reservoirs under the Earth's surface to generate electricity and power heat or water pumps.[1][2]
According to the U.S. Energy Information Administration (EIA), the United States produced 16.8 billion kilowatt hours (kWh) of electricity from geothermal power plants in 2015—0.4 percent of total U.S. electricity generation. As of 2016, seven states had geothermal power plants: California, Hawaii, Idaho, Nevada,New Mexico, Oregon, and Utah.[3][4]
Background
Heat is continually produced by decaying potassium and uranium found in magma (hot and molten rock) below the Earth's surface. Active or geologically young volcanoes generally contain the highest underground temperatures. Areas known as hot spots contain geothermal energy and can be found in states like Alaska, California, Nevada, and Oregon. Rock under the surface is broken up by earthquakes and the movement of magma. Water then rises to the surface, creating geysers and natural hot springs, such as Old Faithful at Yellowstone National Park.[5][6][7]
One method of using geothermal energy involves tapping into areas known as hydrothermal convection systems. The cooler water in these systems enters the Earth's crust and is heated before it rises to the surface. Geothermal plants use holes drilled into the rock to capture steam and to power electric generators. Warm water is then returned to the heat source to maintain its heat.[5][6]
Three types of geothermal plant designs are described below:[5][6]
- A dry steam plant takes steam directly through a turbine to generate electricity and then to a condenser, which changes the steam into water.
- A flash steam plant takes in hot water and de-pressurizes it into steam to drive a turbine.
- A binary cycle power plant takes hot water through a heat exchanger, which contains a liquid known as isobutane. Isobutane, which boils at a lower temperature than water, and water are converted into steam to power a turbine.
History
According to the U.S. Department of Energy, geothermal energy was used in 1864 to heat the Hot Lake Hotel near La Grande, Oregon. In 1892, a district heating system was built using geothermal energy in Boise, Idaho. The first geothermal power plant in the United States was built in 1921 in California.[6][8]
Production and use
According to the U.S. Energy Information Administration (EIA), the United States produced 16.8 billion kilowatt hours (kWh) of electricity from geothermal power plants in 2015—0.4 percent of total U.S. electricity generation. In 2015, the United States consumed 213 trillion British Thermal Units (BTUs) of geothermal energy. As of 2015, the United States had 197 generators of geothermal power.[9][3][10]
The following were the top geothermal energy-producing states in 2015.
| Geothermal energy-producing states (2015) | |
|---|---|
| State | Percentage of U.S. production |
| California | 74% |
| Nevada | 20% |
| Utah | 3% |
| Hawaii | 1.4% |
| Idaho | 0.6% |
| New Mexico | 0.1% |
| Source: U.S. Energy Information Administration, "Geothermal Use" | |
Production on federal lands
Some federal lands can be leased for energy production, including geothermal energy. From 2008 to 2015, the U.S. Bureau of Land Management leased approximately 1 million acres of federal land for geothermal energy in the following states:[11]
Regulation
The Geothermal Steam Act authorizes the secretary of the U.S. Department of the Interior to lease federal lands for geothermal development. The act excludes national parks, lands managed by the U.S. Fish and Wildlife Service, and wildlife refuges from geothermal development. The U.S. Bureau of Land Management (BLM) issues leases for exploring, developing, and producing geothermal energy. Leaseholders have ten years to reach a level of geothermal production specified in their leases. If geothermal resources are developed at this level, the BLM can extend the lease to 40 years with opportunities for lease renewals afterward. The act requires the BLM to hold competitive bidding auctions for leases, the agency collects rents and royalties on geothermal production.[8][12]
Energy in the 50 states
Click on a state below to read more about that state's energy policy.
See also
Footnotes
- ↑ U.S. Energy Information Administration, “Glossary, G,” accessed January 29, 2014
- ↑ Energy Informative, "Geothermal Energy Pros and Cons," June 1, 2013
- ↑ 3.0 3.1 Institute for Energy Research, "Geothermal," accessed Jule 1, 2016
- ↑ U.S. Department of Energy, "Electricity Generation," accessed July 1, 2016
- ↑ 5.0 5.1 5.2 Union of Concerned Scientists, "How Geothermal Energy Works," December 22, 2014
- ↑ 6.0 6.1 6.2 6.3 U.S. Energy Information Administration, "Geothermal Basics," accessed November 11, 2014
- ↑ U.S. Department of Energy, "Electricity Generation," accessed July 1, 2016
- ↑ 8.0 8.1 U.S. Department of Energy, "A History of Geothermal Energy in America," accessed July 1, 2016
- ↑ U.S. Energy Information Administration, "Table 10.1 Renewable Energy Production and Consumption by Source," accessed March 10, 2017
- ↑ U.S. Energy Information Administration, "Table 4.3. Existing Capacity by Energy Source, 2015 (Megawatts)," accessed March 10, 2017
- ↑ U.S. Bureau of Land Management, "Renewable Energy: Geothermal Renewable Energy: Geothermal," accessed March 10, 2017
- ↑ U.S. Bureau of Land Management, "The Geothermal Steam Act of 1970," accessed March 10, 2017
