How Many Geothermal Power Plants Are There In The United States?
Geothermal energy is thermal energy generated and stored in the Earth. It is a renewable source of energy that utilizes heat from the Earth’s core to produce steam and hot water that can generate electricity. Geothermal power plants use wells and pumps to bring this heated underground water to the surface as a geofluid, which powers turbines to generate electricity.
The United States is the largest producer of geothermal energy in the world. Geothermal power plants in the US provide clean, renewable baseload electricity around the clock. As of 2021, there are 25 countries worldwide using geothermal energy for electricity production or direct heat applications.
History of Geothermal Power in the US
The first geothermal power plant in the United States opened at The Geysers in northern California in 1960 [1]. It was built by Pacific Gas and Electric and had a capacity of 11 MW. Growth was initially slow, with only two more geothermal plants built in the next decade. However, the geothermal power industry expanded more rapidly starting in the 1970s due to the OPEC oil embargo and subsequent increase in oil prices. This drove more interest in developing alternative energy sources like geothermal. By 1980, there were over 500 megawatts of installed geothermal capacity from plants primarily located in California and Nevada [2]. Capacity continued to grow in the 1990s and 2000s, reaching over 2,500 MW by 2010.
Geographic Distribution
Most geothermal power plants in the United States are located in western states where geothermal resources are abundant near the earth’s surface. According to the U.S. Energy Information Administration, the Western U.S. has the highest geothermal energy potential due to its location along tectonic plate boundaries. https://www.eia.gov/energyexplained/geothermal/where-geothermal-energy-is-found.php
Many geothermal plants are clustered in California, Nevada, Utah, Hawaii, and Alaska where there are geothermal reservoirs relatively close to the surface. California generates the most geothermal electricity, accounting for over 45% of total U.S. geothermal power generation. The Geysers complex in northern California is the largest group of geothermal power plants in the world. Nevada and Utah have geothermal plants near fault lines and hot springs. Hawaii and Alaska have plants that tap into volcanic activity to generate power. Overall, the western coastal states, Gulf Coast region, Hawaii, and Alaska have the highest concentration of geothermal power plants due to accessible geothermal resources.
Capacity and Generation
As of 2022, the total installed geothermal power capacity in the United States was 3,812 MW, generating an estimated 16,810 GWh annually. This accounts for 0.4% of total US electricity generation. California leads geothermal capacity with 2,732 MW installed, followed by Nevada (446 MW), Utah (427 MW), and Hawaii (208 MW) [1].
The United States has tapped less than 4% of its estimated geothermal potential capacity. With continued technological advances that enable access to greater depths and higher temperatures, there is significant room for growth. The US Department of Energy estimates the geothermal resource base to be over 30,000 MW [2]. However, growth has been constrained by project development costs and policy uncertainty.
Technology
There are three main types of geothermal power plant technologies used in the United States: flash steam, binary cycle, and dry steam plants [1]. Each type is suited to different geological conditions and can operate at varying scales.
Flash steam plants are the most common, making up about 65% of installed geothermal capacity in the US [2]. They use water at temperatures over 182°C that is pumped under high pressure to generation equipment at the surface. The drop in pressure causes the hot water to convert to steam to drive turbine generators.
Binary cycle power plants use moderate-temperature water (100-182°C) to heat a secondary fluid with a much lower boiling point than water. The secondary fluid vaporizes and drives the turbines. These plants emit essentially no greenhouse gases but currently make up just 5% of geothermal capacity in the US.
Dry steam plants, only suitable in rare locations with naturally occurring steam, account for about 30% of US geothermal capacity. They directly use the steam from below ground to turn turbines [3].
Environmental Impact
Geothermal power plants have relatively low emissions compared to fossil fuel plants. According to the Union of Concerned Scientists, geothermal plants emit on average just 5% of the carbon dioxide of a fossil fuel plant per kilowatt-hour. The low emissions are because geothermal plants tap heat already in the Earth rather than burning fossil fuels to create energy.
However, geothermal plants can impact land use and water consumption. Building a geothermal power plant requires drilling wells deep underground, which can disturb land surfaces. And pumping the hot water from underground reservoirs for generating electricity can deplete freshwater resources if not managed properly, according to the US Energy Information Administration.
Proper siting, fluid injection, and advanced technologies can help mitigate some of the potential environmental effects of geothermal development. With careful management, geothermal can provide clean renewable energy with minimal environmental footprint.
Economics
The levelized cost of electricity (LCOE) is an important economic metric used to compare different energy generating technologies. According to the International Renewable Energy Agency (IRENA), the global weighted average LCOE of geothermal power projects commissioned in 2022 was $0.056 per kWh, around 22% lower than projects commissioned in 2021. This makes geothermal power competitive with other renewable energy sources like onshore wind and utility-scale solar PV (IRENA report).
The LCOE range for geothermal energy generation worldwide in 2022 was between $0.046 and $0.122 per kWh, with an average of around $0.07 per kWh according to Statista (Statista data). This is lower than the LCOE for natural gas and coal power plants. Geothermal’s position as a baseload renewable resource with a relatively low LCOE makes it an attractive option for utilities and policymakers looking to transition to clean energy.
However, project risk factors like resource uncertainty and drilling success rate can significantly impact geothermal LCOE (Park et al.). More exploration and technical improvements to reduce risk could help lower geothermal LCOE further. Overall, geothermal energy has proven itself as an economical source of renewable baseload power.
Policy and Incentives
The federal government offers tax credits to encourage the adoption of geothermal energy in the United States. The federal geothermal tax credit allows homeowners to deduct a percentage of the cost of installing a geothermal heat pump system from their federal taxes. The tax credit started at 30% for systems installed between 2016-2019, dropped to 26% for systems installed in 2020-2022, and will be 22% for systems installed in 2023 [1]. This incentive makes geothermal systems more affordable for homeowners.
Many U.S. states also offer additional incentives for geothermal system installation, such as rebates, grants, loans and sales tax exemptions. For example, California offers rebates up to $1,500 per ton for new residential geothermal heat pump installations [2]. Other states like Idaho, Nevada and Oregon also offer generous incentives to promote geothermal adoption [3].
The federal renewable electricity production tax credit (PTC) also supports utility-scale geothermal electricity generation. Qualifying geothermal plants can receive tax credits based on electricity generation for up to 10 years after coming online [4]. This further incentivizes geothermal power deployment in the U.S.
Future Outlook
The future looks bright for geothermal energy in the United States. According to the U.S. Department of Energy, geothermal capacity is projected to grow to 16.5 GW by 2050, a 150% increase from 2022 levels.
Much of this growth will be driven by enhanced geothermal systems (EGS). EGS involves injecting fluid into deep underground reservoirs to fracture hot rock and improve its permeability. This allows geothermal power to be harnessed from areas without natural hydrothermal resources.
According to a DOE report, EGS could provide 100 GW of geothermal capacity in the western U.S. alone. With continued technology improvements, EGS may allow geothermal to expand beyond the western states.
Geothermal is expected to play an important role in firming variable renewable sources like wind and solar. Its ability to provide constant baseload power makes it a valuable component of a decarbonized grid. With supportive policies and sustained research, geothermal can become a major renewable electricity provider in the coming decades.
Number of Plants in the US
According to the Geothermal Energy Association, there are currently 59 operating geothermal power plants with a total installed capacity of 3,677 MW in the United States as of 2019. The Western U.S. has the highest concentration of geothermal plants, with California leading with over 40 geothermal power plants. Other top geothermal producing states include Nevada, Utah, Hawaii, Idaho and Oregon.
The development of geothermal power in the U.S. began in the early 1960s. While growth was slow initially, installed geothermal capacity has more than doubled since 2000. The geothermal industry expects strong continued growth, projecting over 5,600 MW of geothermal power online by 2025. This growth is driven by supportive government incentives, rising energy prices, and the baseload, renewable attributes of geothermal power.
