The largest geothermal power plant in the world 2026: ranking of the biggest geothermal complexes

Updated on 27 October 2026. According to Guinness World Records, the largest geothermal power plant in the world is The Geysers, in California, with 1,517 MW installed across 22 plants. But that record dates from 2014. Today its operator, Calpine (a Constellation subsidiary), reports 13 plants with about 719 net MW, and by installed capacity it is overtaken by the Tuscany geothermal complex in Italy (916 gross MW in 34 plants, in Larderello-Travale and Amiata) and Kenya's Olkaria field (about 909 MW, adding up the plants of KenGen and Ormat).

Chile has a single geothermal power plant: Cerro Pabellón, in the municipality of Ollagüe (Antofagasta Region), with 81 MW. It was the first geothermal power plant in South America and, at 4,500 metres above sea level, one of the highest in the world. This ranking brings together the largest geothermal complexes with the latest figures from their operators.

Geothermal capacity is not measured the same way everywhere. Some operators report gross capacity (what the turbines generate) and others net capacity (what reaches the grid after the plant's own consumption). That is why the table shows which figure applies to each complex. Differences of a few dozen megawatts among the top three fall within that margin.

The Olkaria figure is our own sum: 769 MW from the plants KenGen lists on its geothermal page (excluding the 2.44 MW at Eburru, which is in another field) plus about 140 MW from Ormat's Olkaria III complex. Neither operator publishes a total for the field, so the figure should be read as approximate.

The Geysers spreads over about 117 square kilometres in the Mayacamas Mountains, across Sonoma and Lake counties, north of San Francisco. According to Calpine's 2025 fact sheet, it runs 13 plants (10 in Sonoma and 3 in Lake), had a maximum capacity of 694 net MW in 2024 and generated 5,471,562 net MWh that year. In June 2026 the company completed a 25 MW expansion that will supply more than 25,000 homes, according to Constellation, which describes it as the largest operating geothermal complex in the world.

The gap with the Guinness figure is explained by the field's history. The Geysers once had 22 plants and 1,517 MW installed, of which only 900 MW were in use when Guinness updated its entry in 2014. Steam pressure fell after decades of exploitation and several plants were shut down. Since the late 1990s the field has been recharged with treated wastewater from nearby cities, injected underground to produce steam again.

Larderello, in Tuscany, is the oldest geothermal field in the world: the first light bulb powered by geothermal energy was lit there in 1904, and the first commercial plant began operating in 1913. Today Enel Green Power runs 34 plants across the provinces of Pisa, Siena and Grosseto, with 916 gross MW and output of almost 6 billion kWh a year, according to a Tuscany Region statement. The figure matches the 916 MW that ThinkGeoEnergy assigns to all of Italy, since nearly all Italian geothermal power is in that region. The complex is split into two areas: Larderello-Travale and Mount Amiata, about 80 km away.

Olkaria, in the Rift Valley, inside Hell's Gate National Park, is the engine of geothermal power in Kenya, the African country that generates the most electricity from the Earth's heat. KenGen lists the Olkaria I plants there (45 MW plus units 4, 5 and 6), Olkaria II (105 MW), Olkaria IV (140 MW), Olkaria V (172 MW) and 14 wellhead units (81 MW). On top of that comes Ormat's private Olkaria III complex. KenGen is also preparing Olkaria VII, of 80.3 MW, approved by the Kenyan government in 2025.

Further down are Cerro Prieto, in Baja California (Mexico), with 570 MW installed according to 2020 data compiled in the journal Geothermal Energy (it reached 720 MW before units were retired); Sarulla, in Indonesia, with 330 MW now running at about 220 MW due to changes in reservoir pressure, according to ThinkGeoEnergy; and Hellisheiði, in Iceland, with 303 MW of electricity plus heating for Reykjavík.

The world had 17,173 MW of geothermal capacity at the end of 2025, according to ThinkGeoEnergy's annual count. It is a small share of renewable electricity: it grows by about 300 MW a year, according to IRENA, against hundreds of gigawatts of solar and wind. Its value lies in generating 24 hours a day, regardless of the weather, something it shares with reservoir hydropower, as the ranking of the largest hydroelectric power plant in the world shows. To see how the total breaks down by country, check the ranking of countries with the most renewable electricity.

Source: ThinkGeoEnergy, Top 10 geothermal countries at year-end 2025, published on 12 January 2026. Chile's figure is the Cerro Pabellón capacity reported by Enel.

Cerro Pabellón was inaugurated in September 2017 with two units of 24 MW each, according to ThinkGeoEnergy. It belongs to Geotérmica del Norte, a company in which Enel Green Power Chile holds 83.65% and the state-owned ENAP 16.35%. In 2019 construction began on a third 33 MW unit, with an investment of about US$100 million, which brought the plant to 81 MW. With all three units, its owners estimated output of about 600 GWh a year and 470,000 tonnes of CO2 avoided.

The plant sits on the Altiplano, near the border with Bolivia, in the same region where large-scale copper mining accounts for a big share of the country's electricity use. Mining is now the main buyer of clean energy in the north, as the breakdown of renewable energy in Chilean mining shows. A geothermal plant delivers stable power day and night, a feature that Chile's solar-dominated grid values more and more.

At 81 MW, Cerro Pabellón is less than a tenth of the large complexes in the ranking. Chile has high geothermal potential thanks to its volcanic chain, but exploration costs, the altitude of the reservoirs and permitting have held back other projects. As of October 2026 there is no second geothermal plant in operation in the country.

The ranking groups by geothermal complex or field the installed capacity reported by operators or official sources, with the date of each figure. The most recent figure available as of October 2026 was used. When an operator does not publish a total, as in Olkaria, the plants listed by each company were added up. The list will be updated on this same page when the figures change.

What is the largest geothermal power plant in the world?

Guinness World Records names The Geysers (California), with 1,517 MW according to its 2014 entry. With current data, Enel's Tuscany complex (916 gross MW) and Kenya's Olkaria field (about 909 MW) report more capacity than The Geysers (about 719 net MW).

Which country produces the most geothermal power?

The United States, with 3,953 MW at the end of 2025, followed by Indonesia (2,742 MW) and the Philippines (2,034 MW).

Does Chile have geothermal power plants?

One: Cerro Pabellón, in Ollagüe (Antofagasta Region), with 81 MW. It is the first geothermal power plant in South America.

Where was the world's first geothermal power plant built?

In Larderello (Italy). The first tests took place there in 1904, and the first commercial plant began operating in 1913.

Energía Futura (2026). The largest geothermal power plant in the world 2026: ranking of the biggest geothermal complexes. With data from Guinness World Records, Calpine, Constellation, Enel Green Power, Tuscany Region, KenGen, Ormat, CFE, ThinkGeoEnergy and Enel Chile, accessed on 27 October 2026. Available at https://energiafutura.cl/en/news/the-largest-geothermal-power-plant-in-the-world-2026-ranking-of-the-biggest-geothermal-complexes. The cover chart may be reproduced with credit to Energía Futura and a link to this page.