Geothermal energy Geothermal energy is the thermal energy in the Earth's crust which originates from the formation of the planet and from radioactive decay of materials in currently uncertain but possibly roughly equal proportions. The high temperature and pre ...

was first used for

electric power Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions ...

production in the United States in 1960. The Geysers in Sonoma and

Lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

counties,

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

was developed into the largest geothermal steam electrical plant in the world, at 1,517

megawatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after Jame ...

s. Other geothermal steam fields operate in the western US and Alaska. Geothermal power can be dispatchable to follow the demands of changing loads. Its environmental impact includes

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The und ...

emissions, corrosive or saline chemicals discharged in waste water, possible seismic effects from injection into rock formations, waste heat and noise.

History

Archaeological evidence documents that geothermal resources have been in use in the US for more than 10,000 years. Paleo-Indians first used geothermal

hot springs A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by c ...

for warmth, cleansing, and minerals. Pacific Gas and Electric opened the US' first commercial geothermal power plant at The Geysers in

in September 1960, initially producing eleven megawatts of net power. The Geysers system grew into the world's largest, with an output of 750 MW. It exploits the largest dry steam field, north of

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

. The original turbine lasted for more than 30 years. Near Several small power plants were built during the late 1980s in the Basin and Range geologic province in

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

, southeastern

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idah ...

, southwestern

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and W ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...

and western

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

. is now an area of rapid geothermal development. In the

Salton Sea The Salton Sea is a shallow, landlocked, highly saline body of water in Riverside and Imperial counties at the southern end of the U.S. state of California. It lies on the San Andreas Fault within the Salton Trough that stretches to the Gu ...

, as of 2001, 15 geothermal plants were producing electricity. Hudson Ranch I geothermal plant, a 50 MW plant opened in May 2012. A second similar plant was to open in 2013.49.9-MW Hudson Ranch I Geothermal Plant Unveiled in California
Meg Cichon, RenewableEnergyWorld.com The most significant development catalyst 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.6 Million American Households to be Powered by Geothermal Energy, New Survey Reports
In April 2008, exploratory drilling began at Newberry Volcano in

. As of August 2008, 103 new projects were under way in 13 US states. When developed, these projects could potentially supply up to 3,979 MW of power, meeting the needs of about 4 million homes. The DOE Geothermal Technologies Program (part of the

American Recovery and Reinvestment Act of 2009 The American Recovery and Reinvestment Act of 2009 (ARRA) (), nicknamed the Recovery Act, was a stimulus package enacted by the 111th U.S. Congress and signed into law by President Barack Obama in February 2009. Developed in response to the Gr ...

) allowed the USDOE to fund research in Enhanced Geothermal Systems (EGS) to learn more about the fracture systems in geothermal reservoirs and better predict the results of reservoir stimulation. In 2009, investment bank Credit Suisse calculated that geothermal power costs 3.6 cents per kilowatt-hour, versus 5.5 cents per kilowatt-hour for coal, if geothermal receives subsidized loans. A report released in late May 2019 by the Department of Energy suggests that US geothermal power capacity could increase by more than twenty-six times by 2050, reaching a capacity of 60 GW, thanks to accelerated technological development and adoption. The report documented the benefits of geothermal power for residential and industrial heating. Energy Secretary

Rick Perry James Richard Perry (born March 4, 1950) is an American politician who served as the 14th United States secretary of energy from 2017 to 2019 and as the 47th governor of Texas from 2000 to 2015. Perry also ran unsuccessfully for the Republi ...

announced his Department had provided funding for a $140-million research facility at the University of Utah on man-made geothermal energy. In 2018, due to volcanic activity the Puna Geothermal Venture in Hawaii had to be closed and was inundated by lava flows. It reopened in November 2020.

Production

With 3,676 MW of installed geothermal capacity as of 2019, the US remains the world leader with about 25% of the online capacity total. 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.

By state

Installed geothermal capacity in megawatts (MW) by state as of February 2012:

Geysers

The Geysers has 1517

(MW) of active installed capacity with an average capacity factor of 63%. Calpine Corporation owns 15 of the 18 active plants in the Geysers and is the US' largest producer of geothermal energy. Two other plants are owned jointly by the Northern California Power Agency and Silicon Valley Power. The remaining

Bottle Rock Power Plant The Bottle Rock Power Plant (BRPP) is a geothermal power plant in the Glenbrook Area of Lake County, California, United States. Location The Bottle Rock Power Plant is within a leasehold near the town of Cobb on High Valley Road, Glenbrook Ar ...

is owned by the US Renewables Group. A nineteenth plant is under development by Ram Power. The Geysers is recharged by injecting treated sewage effluent from the City of Santa Rosa and the Lake County sewage treatment plant. This 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.

Salton Sea

Another major geothermal area is located in south central

, on the southeast side of the

, near

Niland Niland is a surname. Notable people with the surname include: * Conor Niland (born 1981), tennis player * D'Arcy Niland (1917–1967), author * Deborah Niland (born 1950), illustrator * Elly Niland (born 1954), poet * John Niland (born 1940), ac ...

and Calipatria, California. 15 geothermal plants combine for a capacity of about 570 MW. CalEnergy owns about half of them and the rest are owned by various companies.

Basin and Range

The Basin and Range geologic province in

, southeastern

, southwestern

and western

hosts 19 geothermal power plants in Nevada that produce more than 486 MW. The largest plant is the McGinnis Hills facility operated by Ormat with a capacity of 96MW. Other geothermal plants in Nevada are at Steamboat Springs, Brady/Desert Peak, Dixie Valley, Soda Lake, Stillwater and Beowawe.

Reliability

McGinness Hills Pipelines with Expansion Joints

Unlike power sources such as wind and solar, geothermal energy is dispatchable, meaning that it is both available whenever needed, and can quickly adjust output to match demand. According to the US Energy Information Administration (EIA), of all types of new electrical generation plants, geothermal generators have the highest

capacity factor The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is def ...

, a measure of how much power a facility actually generates as a percent of its maximum capacity. The EIA rates new geothermal plants as having a 92% capacity factor, comparable to those of nuclear (90%), and higher than gas (87%), or coal (85%), and much higher than those of intermittent sources such as onshore wind (34%) or solar photovoltaic (25%). 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.

National Geothermal Data System

The US operates the

National Geothermal Data System The National Geothermal Data System (NGDS) is an American Distributed computing, distributed data network that collects and provides public access to digital Geothermal energy, geothermal exploration and development information. Data includes bore ...

(NGDS). Through the NGDS, many older paper archives and drill logs stored at state geological surveys are now being digitized and made available for free to the public.

Cost

Environmental effects

The underground hot water and steam used to generate geothermal power may contain chemical pollutants, such as hydrogen sulfide (). is toxic in high concentrations, and is sometimes found in geothermal systems. Newer production methods separate the hot steam collected underground from the steam used to power turbines, and substantially reduce the risk of releasing contaminants. The water mixed with the steam contains dissolved salts that can damage pipes and harm aquatic ecosystems. Some subsurface water associated with geothermal sources contains high concentrations of toxic elements such as boron,

lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...

, and

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, bu ...

. Injection of water in enhanced geothermal systems may induce seismicity. Earthquakes at the Geysers geothermal field in California, the largest being Richter magnitude 4.6, have been linked to injected water.Lawrence Berkeley National Laboratory
The Geysers
/ref> "Possible effects include scenery spoliation, drying out of hot springs, soil erosion,

noise pollution Noise pollution, also known as environmental noise or sound pollution, is the propagation of noise with ranging impacts on the activity of human or animal life, most of them are harmful to a degree. The source of outdoor noise worldwide is mai ...

, and chemical pollution of the atmosphere and of surface- and groundwaters."

References

External links

*GA Mansoori, N Enayati, LB Agyarko (2016)
Energy: Sources, Utilization, Legislation, Sustainability, Illinois as Model State
World Sci. Pub. Co.,
Geothermal Energy AssociationGeothermal Resources CouncilGeothermal Lease Auction Signals New Trend in USThe Status of the US Geothermal IndustryScaling Geothermal for Reliable Baseload PowerTechnological Innovation Driving Renewed Interest in Geothermal EnergyInterior Department To Open 190 Million Acres to Geothermal PowerRaser Ready to Deliver Power from Thermo PlantHawaii Groundwater & Geothermal Resources Center by the University of Hawaii at ManoaThe Geothermal Collection by UH ManoaM 5.0 - 8km NW of The Geysers, California
– United States Geological Survey {{Renewable energy by country