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One of 21 power plants at The Geysers, California, the largest geothermal development in the world.

Geothermal energy in the United States continues to be an area of considerable activity. The USA is the world leader in online capacity of geothermal energy and the generation of electricity from geothermal energy.[1]

The first U.S. geothermal power plant, opened at The Geysers in California in 1960, continues to operate successfully. The United States generates an average of 15 billion kilowatt hours of geothermal power per year, comparable to burning some 25 million barrels (4,000,000 m3) of oil or 6 million short tons of coal per year.[2]

Although geothermal power plants, concentrated in the West, provide the third largest domestic source of renewable electricity after hydroelectricity and biomass, they currently produce less than one percent of total U.S. electricity supply. However, a geothermal resource assessment shows that nine western states together have the potential to provide over 20 percent of national electricity needs.[2]



According to archaeological evidence, geothermal resources have been in use on the current territory of the United States for more than 10,000 years. The Paleo-Indians first used geothermal hot springs for warmth, cleansing, and minerals.[2]

The first commercial geothermal power plant producing power to the U.S. utility grid opened at The Geysers in California in 1960, producing eleven megawatts of net power. The Geysers system continues to operate successfully today, and the complex has grown into the largest geothermal development in the world, with an output of 750 MW.[2]


The largest dry steam field in the world is the Geysers, 116 km (72 miles) north of San Francisco. It was here that Pacific Gas and Electric began operation of the first successful geothermal electric power plant in the United States in 1960.[3] The original turbine lasted for more than 30 years and produced 11 MW net power.[4] The Geysers has 1517 megawatt (MW)[5 ] of active installed capacity with an average capacity factor of 63%.[6] Calpine Corporation owns 15 of the 18 active plants in the Geysers and is currently the United States' largest producer of geothermal energy.[7] Two other plants are owned jointly by the Northern California Power Agency and the City of Santa Clara's municipal Electric Utility (now called Silicon Valley Power). The remaining Bottle Rock Power plant owned by the US Renewables Group has only recently been reopened.[8] A nineteenth plant is now under development by Ram Power, formerly Western Geopower. Since the activities of one geothermal plant affects those nearby, the consolidation plant ownership at The Geysers has been beneficial because the plants operate cooperatively instead of in their own short-term interest. The Geysers is now recharged by injecting treated sewage effluent from the City of Santa Rosa and the Lake County sewage treatment plant. This sewage effluent used to be dumped into rivers and streams and is now piped to the geothermal field where it replenishes the steam produced for power generation.

Another major geothermal area is located in south central California, on the southeast side of the Salton Sea, near the cities of Niland and Calipatria, California. As of 2001, there were 15 geothermal plants producing electricity in the area. CalEnergy owns about half of them and the rest are owned by various companies. Combined the plants have a capacity of about 570 MW.

The Basin and Range geologic province in Nevada, southeastern Oregon, southwestern Idaho, Arizona and western Utah is now an area of rapid geothermal development. Several small power plants were built during the late 1980s during times of high power prices. Rising energy costs have spurred new development. Plants in Nevada at Steamboat near Reno, Brady/Desert Peak, Dixie Valley, Soda Lake, Stillwater and Beowawe now produce about 235 MW.

Production and development

Estimated subterranean temperatures at a depth of 6 kilometers

With 3,040.27 MW of installed geothermal capacity, the United States remains the world leader with 30% of the online capacity total.[1] The future outlook for expanded production from conventional and enhanced geothermal systems is positive as new technologies promise increased growth in locations previously not considered.[9]

As of August 2008, 103 new projects are underway in 13 U.S. states. When developed, these projects could potentially supply up to 3,979 MW of power, meeting the needs of about 4 million homes. At this rate of development, geothermal production in the United States could exceed 15,000 MW by 2025.[9]

The most significant catalyst behind new industry activity is the Energy Policy Act of 2005. This Act made new geothermal plants eligible for the full federal production tax credit, previously available only to wind power projects and certain kinds of biomass. It also authorized and directed increased funding for research by the Department of Energy, and enabled the Bureau of Land Management to address its backlog of geothermal leases and permits.[1]

In April 2008, exploratory drilling began at Newberry Volcano in Oregon.[10]

This quotation was from a March, 2009 article from "The newest report, from international investment bank Credit Suisse, says geothermal power costs 3.6 cents per kilowatt-hour, versus 5.5 cents per kilowatt-hour for coal."[11] [1]


Geothermal has a higher capacity factor (a measure of the amount of real time during which a facility is used) than many other power sources. Unlike wind and solar resources, which are more dependent upon weather fluctuations, geothermal resources are available 24 hours a day, 7 days a week. While the carrier medium for geothermal electricity (water) must be properly managed, the source of geothermal energy, the Earth's heat, will be available, for most intents and purposes, indefinitely.[2][12]

The Stanford Geothermal Program had a noteworthy result, having achieved a proof of concept in the use of tiny particles called nanoparticles as tracers to characterize fractured rocks. The result comes from research funded by USDOE in 2008 to accelerate technology development for Enhanced Geothermal Systems (EGS). This research will help developers learn more about the fracture systems in geothermal reservoirs, so that they may better predict the results of reservoir stimulation. Positive results from DOE-funded research will lead to further development of EGS, a clean energy technology capable of producing baseload electricity across the United States.


Environmental Risk

Acquiring steam from geysers, volcanoes, and hot springs is a process that isn't harmful to the environment. However,the actual steam that is being collected and transferred into energy contains chemicals that contribute to air pollution, and water mixed with the steam consists of dissolved salts that can damage pipes and harm aquatic ecosystems. [13]

In addition to hazardous salts in our environment, some waters that are collected with the process of geothermal energy have contained high concentrations of toxic elements such as boron, lead, and arsenic. A gas that has been found in geothermal water and steam is hydrogen sulfide. Having a bad odor of rotten eggs, is toxic in high concentrations. [14]

See also


  1. ^ a b c 6 Million American Households to be Powered by Geothermal Energy, New Survey Reports
  2. ^ a b c d e A Guide to Geothermal Energy and the Environment
  3. ^ Lund, J. (September 2004), "100 Years of Geothermal Power Production", Geo-Heat Centre Quarterly Bulletin (Klamath Falls, Oregon: Oregon Institute of Technology) 25 (3): 11-19, ISSN 0276-1084,, retrieved 2009-04-13  
  4. ^ McLarty, Lynn; Reed, Marshall J. (October 1992). "The U.S. Geothermal Industry: Three Decades of Growth". Energy Sources, Part A: Recovery, Utilization, and Environmental Effects (London: Taylor & Francis) 14 (4): pp. 443 - 455. doi:10.1080/00908319208908739. ISSN 1556-7230.  
  5. ^ DiPippo, Ronald. Geothermal Power Plants, Second Edition: Principles, Applications, Case Studies and Environmental Impact. Butterworth-Heinemann. ISBN 978-0-7506-8620-4.  
  6. ^ Lund, John W.; Bloomquist, R. Gordon; Boyd, Tonya L.; Renner, Joel (24-29 April 2005), "The United States of America Country Update", Proceedings World Geothermal Congress, Antalya, Turkey,, retrieved 2009-11-9  
  7. ^ All figures adjusted to include recently reopened Bottle Rock Power plant.
  8. ^ Baker, David R. (Sunday, January 14, 2007). "Steamy industry may clear the air". San Francisco Chronicle (Lake County): p. page F-1. Retrieved 2009-11-09.  
  9. ^ a b Update: The State of U.S. Geothermal Production and Development
  10. ^ Gail Kinsey-Hill (2008-06-03). "Company Seeks Power From Crater". Vancouver Sun. p. B2.  
  11. ^ Mims, Christopher. “Can Geothermal Power Compete with Coal on Price?” Scientific American. N.p., 2 Mar. 2009. Web. 9 Oct. 2009. <‌article.cfm?id=can-geothermal-power-compete-with-coal-on-price>.
  12. ^ Geothermal 101: Basics of Geothermal Energy Production and Use p. 5 & 7.
  13. ^ “Alternative Energy Sources.” UXL Encyclopedia of Science. Ed. Rob Nagel. 2nd ed. Detroit: UXL, 2007. Student Resource Center Gold. Web. 9 Oct. 2009.
  14. ^ McFarland, Ernest L. “Geothermal Energy.” Macmillan Encyclopedia of Energy. Ed. Ed John Zumerchik. Vol. 2. New York: Macmillan Reference USA, 2001. 572-579. Gale Virtual Reference Library. Web. 9 Oct. 2009.

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