Geothermal power plants are concentrated along tectonic plate boundaries and volcanic zones, with at least 28 countries generating geothermal electricity as of 2024. Global installed capacity reached roughly 15.1 gigawatts that year. The largest clusters sit in the western United States, Southeast Asia’s Ring of Fire, East Africa’s Rift Valley, and volcanic hotspots like Iceland and New Zealand.
Why Location Matters
Geothermal plants need underground heat close enough to the surface to be economically tapped. That heat comes from magma chambers, volcanic activity, and the friction of colliding tectonic plates. The best sites share a few features: active or recent volcanism, faults and fractures that let hot fluids rise, and surface clues like steam vents and hot springs. This is why the global map of geothermal plants closely mirrors the map of the world’s most seismically active zones.
Top 10 Countries by Installed Capacity
The International Geothermal Association tracks capacity by country. The current rankings, in megawatts of electricity generation:
- United States: 3,889 MW
- Indonesia: 2,335 MW
- Philippines: 1,952 MW
- Turkey: 1,717 MW
- New Zealand: 1,055 MW
- Mexico: 1,002 MW
- Kenya: 952 MW
- Italy: 916 MW
- Japan: 546 MW
- Costa Rica: 253 MW
Together, these ten countries account for the vast majority of global geothermal power. What they share is geography: each sits on or near active plate boundaries or volcanic systems.
United States: The Western States
Nearly all U.S. geothermal plants are in the western states and Hawaii, where underground heat sits close to the surface. California dominates, producing more geothermal electricity than any other state. The centerpiece is The Geysers, a dry steam reservoir in the Mayacamas Mountains north of San Francisco. It spans 45 square miles across Lake, Mendocino, and Sonoma counties. Eighteen active plants there produce about 835 megawatts, making it the largest dry steam geothermal field in the world. It has been generating electricity since 1960.
Nevada hosts the second-largest concentration of geothermal plants in the country, with dozens of smaller facilities spread across the state’s Basin and Range geology. Utah, Oregon, and Hawaii also have operating plants, all tied to the volcanic and tectonic activity that defines the western landscape.
Indonesia and the Philippines
Indonesia and the Philippines rank second and third globally, and the reason is simple: both countries sit squarely on the Pacific Ring of Fire, the horseshoe-shaped belt of plate boundaries that circles the Pacific Ocean. Indonesia alone has more than a dozen major geothermal fields. The largest include Gunung Salak (377 MW), Darajat (270 MW), Wayang Windu (227 MW), and Kamojang (235 MW), all on the island of Java. Additional plants operate in Sumatra (Ulubelu, Sibayak, Sarulla) and Sulawesi (Lahendong).
The Philippines similarly draws its geothermal energy from volcanic islands, with major fields on the islands of Luzon, Leyte, and Negros. The country’s location on the same volcanic arc gives it one of the highest shares of geothermal power in its national electricity mix.
Italy: Where It All Started
The world’s first geothermal power plant was built in 1904 at Larderello in Tuscany, Italy. More than a century later, the Larderello field still operates, providing power to about one million households. Italy’s total installed geothermal capacity is around 916 MW, concentrated in the Tuscan region where volcanic heat from deep within the Italian peninsula reaches the surface.
Iceland
Iceland sits on the Mid-Atlantic Ridge, where the North American and Eurasian tectonic plates pull apart. That position gives the island abundant geothermal resources. Total installed geothermal power generation capacity is about 753 MW. The two most prominent plants are Hellisheiði and Nesjavellir, both located in the volcanic highlands east of Reykjavík.
Nesjavellir sits about 177 meters above sea level and pumps hot water through 23 kilometers of pipes to provide district heating for the greater Reykjavík area, losing only 2°C along the way. Hellisheiði uses a process called Carbfix to capture roughly 75% of the hydrogen sulfide and 30% of the carbon dioxide from its geothermal fluids and reinject them underground, making it one of the cleaner geothermal operations in the world.
Kenya and the East African Rift
Kenya is Africa’s geothermal leader, with nearly all of its capacity centered on the Olkaria geothermal field in the Great Rift Valley. Olkaria is the largest geothermal field on the continent. The Kenya Electricity Generating Company (KenGen) operates 754 MW of geothermal capacity, which accounts for about 44% of the company’s total power generation. Kenya produces more than 90% of its electricity from renewable sources, and geothermal is a major reason why.
Expansion is underway. KenGen plans to drill 42 new wells at Olkaria to add another 200 MW, part of a $1.8 billion investment over five years aligned with the country’s goal of 100% renewable energy by 2030. The Rift Valley’s geology, with its thin crust, active faulting, and shallow magma chambers, makes it one of the most promising geothermal regions on Earth. Ethiopia, Djibouti, and Tanzania also have geothermal potential along the same rift system, though development there is still in early stages.
Other Notable Locations
Turkey has climbed to fourth place globally with over 1,700 MW, concentrated in the western Anatolian region where tectonic extension creates geothermal reservoirs. New Zealand’s plants cluster in the Taupo Volcanic Zone on the North Island, a region shaped by the subduction of the Pacific Plate. Mexico’s largest geothermal field, Cerro Prieto in Baja California, has been producing since the 1970s. Costa Rica and Japan round out the top ten, both drawing on volcanic geology to fuel their plants.
Expanding Beyond Volcanic Zones
Traditional geothermal plants depend on naturally occurring underground reservoirs of hot water or steam. A newer approach called enhanced geothermal systems (EGS) could change the map entirely. EGS works by drilling into hot, dry rock, injecting water to create fractures, and circulating that water to extract heat, even in places with no natural geothermal reservoir.
The U.S. Department of Energy is funding three EGS pilot projects. One is in Sonoma County, California, near The Geysers. A second, run by Fervo Energy, is in the Milford Renewable Energy Corridor in Utah, at a site with no existing commercial geothermal production, aiming to produce at least 8 MW per well. A third, on the western flank of Newberry Volcano in Oregon, is testing “super-hot” EGS at temperatures above 375°C. A fourth round of funding specifically targets the eastern United States, where conventional geothermal resources are scarce but deep rock temperatures could still be harnessed.
If EGS proves commercially viable at scale, geothermal energy could eventually move well beyond its current footprint along plate boundaries and into regions that have never had access to underground heat for electricity.