Geothermal energy is actively used across eight U.S. states, with 99 power plants generating a combined 3,969 megawatts of electricity as of 2024. Nearly all of this capacity sits in the western half of the country, where volcanic activity and hot underground rock formations lie close enough to the surface to tap. Beyond electricity, geothermal energy heats buildings, warms greenhouses, and supplies hot water in communities from Idaho to Oregon.
California Dominates U.S. Geothermal Production
California is far and away the largest producer of geothermal electricity in the country, hosting 53 of the nation’s 99 geothermal power plants. Those facilities account for 2,868 megawatts of installed capacity, roughly 72% of the entire U.S. total. The state’s geothermal output is anchored by two major resource areas: The Geysers in Sonoma and Lake counties, and the Salton Sea region in Imperial County.
The Geysers, located about 70 miles north of San Francisco, is the largest complex of geothermal power plants in the world. Spread across 45 square miles, its plants produce a net 725 megawatts of electricity, enough to power a city the size of San Francisco. The field is a dry-steam reservoir, meaning it produces steam directly from underground rather than requiring the extra step of flashing hot water into vapor. Fifteen plants currently operate at the site.
Nevada, Utah, and the Rest of the West
Nevada ranks second nationally with 32 geothermal power plants and 892 megawatts of installed capacity. The state’s geothermal resources are spread across its northern and western basins, where the earth’s crust is thin and fractured enough to allow heat to rise close to the surface. A 2008 auction of public lands in Nevada brought in a record $28.2 million for geothermal leasing rights on over 105,000 acres, signaling strong industry interest in expanding there.
Oregon and Utah each operate four geothermal plants. Hawaii and Alaska have two apiece, and Idaho and New Mexico round out the list with one each. Most of these plants are smaller operations, but Utah is poised for significant growth thanks to a new project called Cape Station in Beaver County. Developed by Fervo Energy, Cape Station uses enhanced geothermal technology (drilling into hot rock and injecting water to create a reservoir where none existed naturally). The facility is expected to deliver 100 megawatts to the grid by 2026, with plans to scale to 500 megawatts by 2028. If completed on schedule, it would become the largest next-generation geothermal development in the world.
Federal Lands Play a Major Role
Much of the geothermal activity in the U.S. happens on public land managed by the Bureau of Land Management. The BLM currently manages over 800 geothermal leases, with more than 50 in active producing status. Those leases generate approximately 1,648 megawatts of geothermal energy on federal land alone. An additional 111 million acres of BLM-managed land and 79 million acres of Forest Service land have been designated as open for future geothermal leasing, creating a massive pipeline for potential development across the West.
Heating Buildings in Boise and Beyond
Geothermal energy isn’t just used for electricity. In Boise, Idaho, hot water from a geothermal aquifer beneath the city heats buildings directly, no power plant required. Boise operates the largest geothermal district heating system in the nation. It started in 1983 with just 15 buildings and has since grown to serve about 90 buildings covering more than 6 million square feet of indoor space. Hot water is pumped from wells, circulated through building heating systems, and then returned or discharged.
Similar direct-use applications exist in smaller communities across the West. Geothermal water heats greenhouses, fish farms, and spas in places like Klamath Falls, Oregon, and Reno, Nevada. These systems skip the electricity generation step entirely, using the earth’s heat in its simplest form. For communities sitting on the right geology, this can dramatically reduce heating costs and fossil fuel dependence.
How U.S. Capacity Is Growing
Total U.S. geothermal nameplate capacity reached 3.97 gigawatts in 2024, an 8% increase from 3.67 gigawatts in 2020. That growth has been driven partly by traditional expansion in Nevada and California, and partly by the emergence of enhanced geothermal systems that can unlock heat from rock formations previously considered unusable. Fervo Energy’s Cape Station project, backed by $462 million in funding, represents the most visible bet on this technology.
Enhanced geothermal works by drilling deep into hot, dry rock and fracturing it to create pathways for water to circulate. Water is pumped down, heated by the rock, and brought back to the surface to drive a turbine. The technique borrows heavily from oil and gas hydraulic fracturing methods, which means it can theoretically be deployed far beyond the volcanic zones of the western U.S. If the technology proves economically viable at scale, geothermal energy could eventually move beyond its current eight-state footprint.
Environmental Footprint Compared to Other Sources
Geothermal plants produce remarkably low emissions. They release 99% less carbon dioxide and 97% less sulfur compounds than fossil fuel plants of similar size. U.S. geothermal electricity offsets an estimated 22 million metric tons of CO₂ annually, along with 200,000 metric tons of nitrogen oxides and 110,000 tons of particulate matter that would otherwise come from coal plants.
Water use varies by plant design. Binary cycle plants, which keep geothermal fluid in a closed loop and use a secondary fluid to generate steam, consume between 0.24 and 4.21 gallons of water per kilowatt-hour. Flash plants, which release pressurized underground water into steam, use 1.59 to 2.84 gallons per kilowatt-hour. Both are significantly more efficient than conventional coal or natural gas plants, which average around 15 gallons per kilowatt-hour. In arid western states where water is scarce, this difference matters.