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Each card jumps to that country's flagship plant and — where a full country profile exists — its dedicated page. Prefer to read start to finish? Scroll on.
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United States
Full country profile →
The Geysers, California — world's largest single geothermal complex (725 MW), operating since 1960.
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Indonesia
Full country profile →
Salak, Darajat, Wayang Windu — sits on 40% of the world's identified geothermal resources.
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Iceland
Dedicated project page →
Hellisheiði — pioneering the CarbFix CO₂ mineralisation project · geothermal covers ~30% of Iceland's electricity.
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Italy
Jump to Larderello
Larderello-Travale — the world's first geothermal plant, operating since 1904.
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Mexico
Jump to Cerro Prieto
Cerro Prieto — the world's second-largest geothermal complex after The Geysers.
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Kenya
Jump to Olkaria
Olkaria — Kenya generates over 50% of its electricity from geothermal, Africa's largest complex.
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New Zealand
Jump to Wairakei
Wairakei — the world's second-ever geothermal plant, operating since 1958.
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Philippines
Jump to Tiwi
Tiwi and Makban — approximately 25% of the Philippines' electricity comes from geothermal.
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Turkey
Jump to Kizildere
Kizildere — Turkey is among the world's top 5 geothermal producers.
Prefer plants over countries? Jump straight to the world's 12 largest geothermal installations, GPS-located ↓
"The heat beneath our feet is the same heat that formed the Earth 4.5 billion years ago. We did not put it there. We have simply learned to tap it. In Iceland, people have bathed in geothermal pools for a thousand years. We are the newcomers to this energy."
— The Energy Codex · thecodex.expert
Flagship asset
One of the world's largest geothermal stations — 303 MW electric + 200 MW thermal — and home of the CarbFix carbon-to-stone project.
Cluster 1 · What is it?
What geothermal energy is — precisely
Geothermal energy is heat stored in the Earth. The Earth's interior has remained hot for 4.5 billion years — partly from the original heat of planetary formation and partly from the continuous decay of radioactive isotopes (uranium, thorium, potassium) deep in the crust and mantle. This heat flows outward, creating a geothermal gradient of approximately 25–30°C per kilometre of depth everywhere on Earth, and much higher gradients near tectonic plate boundaries and volcanic zones.
In plain English: The Earth is hot inside — extremely hot. That heat leaks upward through the ground. In some places, particularly near volcanoes and the edges of tectonic plates, this heat is close enough to the surface to be practical. Drill a hole, and hot water or steam comes up. Use it to spin a turbine. Unlike solar and wind, geothermal doesn't depend on the weather or time of day — the Earth is always hot. It is the most reliable renewable energy source by a significant margin.
Where geothermal works best: The Ring of Fire (Pacific plate boundaries — USA, Philippines, Indonesia, Japan, New Zealand), the East African Rift Valley (Kenya, Ethiopia), Iceland (Mid-Atlantic Ridge), and Italy (Larderello).
Geothermal gradient: On average 25–30°C per km depth. At tectonic plate boundaries, this can reach 100–200°C per km, making high-temperature resources accessible at 1–3 km depth rather than 5–10 km. This is why Iceland can run its entire heating system and a third of its electricity on geothermal — it sits on the Mid-Atlantic Ridge.
What makes a resource economic: Temperature (>150°C for electricity), permeability (rock must allow fluid flow), and recharge (the fluid must be naturally replenished or can be injected).
Geothermal gradient: On average 25–30°C per km depth. At tectonic plate boundaries, this can reach 100–200°C per km, making high-temperature resources accessible at 1–3 km depth rather than 5–10 km. This is why Iceland can run its entire heating system and a third of its electricity on geothermal — it sits on the Mid-Atlantic Ridge.
What makes a resource economic: Temperature (>150°C for electricity), permeability (rock must allow fluid flow), and recharge (the fluid must be naturally replenished or can be injected).
Source: IRENA Geothermal Power 2023
Earth's total heat flux at the surface: approximately 47 TW, of which ~50% is radiogenic (radioactive decay) and ~50% primordial (formation heat). The geothermal gradient in high-enthalpy zones reaches 80–200°C/km. Hydrothermal systems require: (1) a heat source (magmatic intrusion or elevated gradient), (2) a permeable reservoir rock (fractures, vesicular basalt, limestone), (3) a fluid (groundwater), and (4) a caprock (impermeable layer). Classification: high-enthalpy (>200°C reservoir temperature, electricity generation), medium-enthalpy (100–200°C, binary cycle electricity + heat), low-enthalpy (<100°C, direct use — district heating, agriculture). The thermodynamic efficiency of geothermal electricity generation is limited by the Carnot efficiency ηc = 1 - Tcold/Thot. For a 250°C geothermal fluid rejecting to 50°C ambient: ηc = 1 - 323/523 = 38% theoretical maximum. Actual plant efficiency: 10–23% for flash, 8–14% for binary.
Source: DiPippo, R. "Geothermal Power Plants" (Butterworth-Heinemann, 4th ed.) · IRENA 2023
15.9 GWGlobal capacity (IRENA 2024)
90%+Capacity factor — highest of any source
38 g CO₂/kWhLifecycle (IPCC AR6)
47 TWTotal Earth heat flux
Cluster 3 · Types
Four types of geothermal technology
Dry steam — simplest, oldest
Steam comes directly from the reservoir and drives the turbine. The simplest and most efficient type. Rare — requires a reservoir that naturally produces dry steam. Larderello, Italy (43.23°N 10.88°E) — first used in 1904. The Geysers, California — world's largest geothermal complex (725 MW).
Flash steam — most common
High-pressure hot water (>180°C) is brought to the surface. As pressure drops, some of the water "flashes" to steam. The steam drives the turbine; the remaining water is re-injected. Used in: Iceland, Philippines, New Zealand, USA, Kenya, Mexico. Most of the world's geothermal capacity uses flash technology.
Binary cycle — lower temperatures
Geothermal water (100–180°C) heats a secondary working fluid (typically isobutane or pentane) with a low boiling point in a heat exchanger. The secondary fluid vaporises and drives a turbine. The geothermal water is never exposed to the atmosphere — near-zero emissions. Works at lower temperatures, opening many more resources. Most new geothermal projects use binary cycle technology.
EGS — Enhanced Geothermal Systems
Creates artificial geothermal reservoirs in hot dry rock where natural permeability is insufficient. Two wells are drilled into hot rock (>150°C). Water is injected at high pressure to fracture the rock (hydraulic stimulation), creating a permeable network. Water circulates through the hot rock, returns to surface as steam or hot water, and drives a turbine. EGS could unlock geothermal energy almost everywhere on Earth — not just volcanic zones. Currently at demonstration phase. Fervo Energy (USA) and Quaise Energy are leaders. See section below.
Direct use — heat without electricity
Geothermal heat used directly for: district heating (Iceland, France, China), greenhouses (Netherlands, Iceland), fish farming, industrial processes, and bathing. Iceland uses geothermal for ~90% of home heating. China has the world's largest direct-use geothermal capacity (~40 GWth). Geothermal heat pumps (ground-source heat pumps) use the stable shallow ground temperature (~12–15°C) to heat/cool buildings efficiently globally. Source: IRENA 2023
Cluster 13 · Named instances — major geothermal plants
The world's 12 largest geothermal installations
| # | Plant | Country | GPS | Capacity | Type | Operator |
|---|---|---|---|---|---|---|
| 1 | The Geysers | USA | 38.79°N 122.74°W | 725 MW | Dry steam | Calpine Corporation · Lake and Sonoma counties, California · Operating since 1960 |
| 2 | Larderello-Travale | Italy | 43.23°N 10.88°E | ~800 MW total complex | Dry steam | Enel Green Power · Tuscany · World's first geothermal plant (1904) · 40+ units across the complex |
| 3 | Hellisheiði Built ✓ | Iceland | 64.04°N 21.39°W | 303 MW electric + 400 MW thermal | Flash | ON Power · Reykjanes Peninsula · Also captures CO₂ and injects into basalt rock (CarbFix project) |
| 4 | Salak | Indonesia | 6.72°S 106.73°E | 377 MW | Flash | Star Energy Geothermal · West Java · Indonesia has world's second-largest geothermal capacity after USA |
| 5 | Darajat | Indonesia | 7.19°S 107.73°E | 259 MW | Dry steam | Star Energy · West Java |
| 6 | Wayang Windu | Indonesia | 7.21°S 107.62°E | 227 MW | Flash | Star Energy · West Java |
| 7 | Cerro Prieto | Mexico | 32.42°N 115.30°W | 720 MW | Flash | CFE · Baja California · World's largest single geothermal power station complex after Geysers |
| 8 | Olkaria | Kenya | 0.89°S 36.29°E | ~861 MW (multiple units) | Flash + Binary | KenGen · Great Rift Valley · Kenya generates ~>50% electricity from geothermal · Africa's largest |
| 9 | Wairakei | New Zealand | 38.62°S 176.09°E | 181 MW | Flash | Contact Energy · Taupo Volcanic Zone · Operating since 1958 — world's second geothermal plant |
| 10 | Tiwi | Philippines | 13.47°N 123.69°E | 289 MW | Flash | AP Renewables (Aboitiz) · Albay · Philippines generates ~25% electricity from geothermal |
| 11 | Makban (Mak-Ban) | Philippines | 14.08°N 121.45°E | 458 MW | Flash | AP Renewables · Laguna and Batangas |
| 12 | Kizildere | Turkey | 37.88°N 28.74°E | 170 MW | Flash + Binary | Zorlu Energy · Denizli province · Turkey is among world's top 5 geothermal producers |
GPS: WRI GPPD (CC BY 4.0) · ThinkGeoEnergy database · Operator disclosures · IRENA 2024
Cluster 3 · EGS — the technology that could unlock everywhere
Enhanced Geothermal Systems — geothermal without the volcano
The Earth is hot everywhere — just at different depths. EGS technology creates artificial geothermal reservoirs in hot dry rock, potentially making geothermal energy available anywhere on Earth, not just near volcanic zones. The US Department of Energy estimates EGS could provide over 100 GW of firm, clean baseload power in the USA alone.
How EGS works
Step 1: Drill two wells to depths where rock is hot enough (>150°C — typically 3–10 km).
Step 2: Pump water at high pressure into the first well to hydraulically fracture the rock, creating a network of micro-fractures.
Step 3: Water circulates through the fractured hot rock, absorbing heat. Hot water/steam returns to surface via the second well.
Step 4: Hot fluid drives a binary cycle turbine, generating electricity. Cooled fluid is reinjected.
The key challenge: induced seismicity. Hydraulic fracturing can trigger small earthquakes. The 2006 Basel, Switzerland EGS project was shut down after causing a M3.4 earthquake. Modern projects use careful monitoring and adaptive management to stay below felt thresholds.
Step 2: Pump water at high pressure into the first well to hydraulically fracture the rock, creating a network of micro-fractures.
Step 3: Water circulates through the fractured hot rock, absorbing heat. Hot water/steam returns to surface via the second well.
Step 4: Hot fluid drives a binary cycle turbine, generating electricity. Cooled fluid is reinjected.
The key challenge: induced seismicity. Hydraulic fracturing can trigger small earthquakes. The 2006 Basel, Switzerland EGS project was shut down after causing a M3.4 earthquake. Modern projects use careful monitoring and adaptive management to stay below felt thresholds.
Who is building EGS today
Fervo Energy (USA): Successfully demonstrated EGS at commercial scale at Project Red, Utah (2023) — first commercial EGS project delivering power to the US grid. Building Cape Station (400 MW) in Utah. Google has contracted Fervo for EGS power. Source: Fervo Energy
Quaise Energy (USA): Using millimetre-wave (gyrotron) beams — the same technology as fusion reactors — to vaporise rock and drill 20+ km deep to access near-unlimited heat. Pre-commercial.
SLB (Schlumberger): The world's largest oilfield services company is applying oil and gas drilling expertise directly to EGS development — the same directional drilling, fracturing, and monitoring technology.
US DOE FORGE (Frontier Observatory for Research in Geothermal Energy): Government-funded EGS research project in Milford, Utah (38.52°N 113.02°W). Source: US DOE FORGE
Quaise Energy (USA): Using millimetre-wave (gyrotron) beams — the same technology as fusion reactors — to vaporise rock and drill 20+ km deep to access near-unlimited heat. Pre-commercial.
SLB (Schlumberger): The world's largest oilfield services company is applying oil and gas drilling expertise directly to EGS development — the same directional drilling, fracturing, and monitoring technology.
US DOE FORGE (Frontier Observatory for Research in Geothermal Energy): Government-funded EGS research project in Milford, Utah (38.52°N 113.02°W). Source: US DOE FORGE
Cluster 7 · Companies
Who operates geothermal energy
Enel Green Power · Italy
Subsidiary of Italy's Enel. Operates the Larderello-Travale complex (~800 MW) — the world's most historically significant geothermal complex, operating since 1904. Also geothermal in Chile, Mexico, USA. Total renewable capacity: 63 GW globally. Source: Enel Green Power 2023
Calpine Corporation · USA
Operates The Geysers in California — 725 MW, the world's largest single geothermal complex. Operating since 1960. Uses recycled municipal wastewater from Santa Rosa and Lake County to recharge the steam reservoir — a pioneering sustainability system. Source: Calpine
KenGen · Kenya
Kenya Electricity Generating Company. Operates Olkaria geothermal complex (~861 MW total) in the Great Rift Valley. Kenya now generates over 50% of its electricity from geothermal — one of the world's leading geothermal economies. KenGen has trained African geothermal engineers from Ethiopia, Rwanda, and Djibouti. Source: KenGen Annual Report 2023
ON Power · Iceland
Operates Hellisheiði (303 MW) — Iceland's largest geothermal plant, also running the CarbFix CO₂ mineralisation project. Iceland's entire heating system and 30% of electricity runs on geothermal. ON Power also runs the Blue Lagoon geothermal spa as a commercial operation. Source: ON Power Iceland
Ormat Technologies · USA/Israel
Founded 1965 in Israel. Pioneer of binary cycle geothermal technology — their Organic Rankine Cycle (ORC) units are installed in over 30 countries. Both builds and operates geothermal plants globally. NYSE listed. NYSE: ORA. One of the few vertically integrated companies — designs, manufactures, and operates its own equipment. Source: Ormat Technologies
Pertamina Geothermal · Indonesia
Indonesia sits on 40% of the world's identified geothermal resources — yet has developed only ~10% of its potential. Pertamina Geothermal Energy (PGE), the state enterprise, operates ~1.2 GW and is rapidly expanding. Indonesia could potentially become the world's largest geothermal producer. Source: Pertamina Geothermal Energy
Cluster 4 · Pioneers
The people who created geothermal energy
Piero Ginori Conti · 1865–1939 · First geothermal electricity
Prince Piero Ginori Conti ran the first geothermal electricity experiment at Larderello, Italy on 4 — using steam from natural vents to run a small turbine powering five light bulbs. By 1911, the Larderello plant was generating enough electricity for the local railway. Today the Larderello complex generates ~800 MW. Ginori Conti proved that the Earth's natural steam could reliably power modern equipment. Source: Enel Green Power historical records.
Bjarni Pálsson · 1719–1779 · First systematic study of Icelandic geothermal
Iceland's first physician-general, Bjarni Pálsson, conducted the first systematic scientific survey of Iceland's geothermal hot springs in the 1750s, documenting temperatures, flow rates, and locations. His work began the scientific understanding of Iceland's geothermal resources — resources that now heat 90% of Icelandic homes. Iceland's entire approach to geothermal energy traces its intellectual roots to his surveys. Source: National Museum of Iceland.
Morton Duthie "Dad" Fraser · 1912–1996 · Commercialised The Geysers
American geologist Morton Fraser convinced Pacific Gas & Electric (PG&E) to invest in The Geysers project in the 1950s when geothermal power was considered impractical. His persistence led to the first US geothermal plant going online in 1960 at 11 MW. The Geysers grew to 725 MW, proving large-scale geothermal was viable in the USA. His work is documented in the California Division of Mines records.
Lucien Bronicki · 1931–2022 · Invented the ORC binary turbine
Israeli engineer Lucien Bronicki co-founded Ormat Technologies in 1965 and developed the Organic Rankine Cycle (ORC) turbine — the technology that allows geothermal electricity from low-temperature resources (100–180°C) that could not previously generate power. ORC technology opened approximately 80% more of the world's geothermal resources to electricity production. Ormat's ORC units are installed in over 175 plants across 30+ countries. Source: Ormat Technologies History
Cluster 11 · Future
What institutional sources project
Cluster 12 · Questions
Six questions people ask — answered
How does geothermal energy work?
The Earth is hot inside. In geothermal plants, wells are drilled into zones where this heat is close to the surface — typically near volcanoes or tectonic plate boundaries. Hot water or steam comes up through the wells. Steam drives a turbine and generator directly (dry steam, flash) or heats a secondary fluid that vaporises to drive the turbine (binary cycle). The fluid is then reinjected into the ground, making it sustainable. The Earth generates this heat continuously from radioactive decay and residual formation heat — it will not run out on any human timescale.
Source: IRENA Geothermal Power 2023 · IAEA
Which countries use the most geothermal energy?
The largest geothermal electricity producers are: USA (~3.7 GW, led by The Geysers in California), Indonesia (~2.4 GW), Philippines (~1.9 GW), Turkey (~1.7 GW), New Zealand (~1 GW), Mexico (~1 GW), Kenya (~861 MW), Italy (~800 MW), and Iceland (~750 MW). As a share of national electricity, Iceland generates ~30% from geothermal, Kenya over 50%, and the Philippines approximately 25%. Source: ThinkGeoEnergy Annual Review 2024 · IRENA 2024.
Source: ThinkGeoEnergy Global Geothermal Power Output 2024 · IRENA 2024
Is geothermal energy available in India?
India has identified geothermal resources in several locations — primarily in the Himalayan arc, Puga Valley (Ladakh, 34.02°N 78.32°E), Tattapani (Chhattisgarh), Manikaran (Himachal Pradesh, 32.02°N 77.35°E), and parts of Andhra Pradesh and Rajasthan. The Geological Survey of India and ONGC have surveyed these areas. However, India's geothermal resources are generally low-to-medium enthalpy and have not yet been developed for commercial electricity generation. ONGC drilled exploratory wells at Puga Valley. Geothermal for direct use (heating) has potential in Ladakh and Himalayan regions. Source: Geological Survey of India (GSI) · National Institute of Rock Mechanics.
Source: Geological Survey of India · ONGC geothermal surveys
What is the advantage of geothermal over solar and wind?
Geothermal's key advantage is its capacity factor — the percentage of time it actually produces power. Geothermal plants run at 90%+ capacity factor, meaning they generate electricity nearly continuously, day and night, in any weather. Solar panels produce only during daylight and only when it's not cloudy (capacity factor ~15–25%). Wind turbines depend on wind (capacity factor ~25–45%). Geothermal provides what is called "firm" or "dispatchable" baseload power — reliable generation that doesn't require storage or backup. Its main disadvantage is geographical limitation: high-quality resources are concentrated near plate boundaries and volcanic zones. EGS technology aims to remove this limitation. Source: IRENA · Lazard LCOE 2024.
Source: IRENA Geothermal Power 2023 · Lazard LCOE 2024
How much does geothermal electricity cost?
Geothermal LCOE varies widely depending on resource quality and location. For high-quality hydrothermal resources (the best natural reservoirs), LCOE is approximately $60–90/MWh (Lazard 2024). For binary cycle plants on lower-temperature resources, $80–150/MWh. EGS is currently much higher — $100–200/MWh — but is expected to fall significantly with scale. Once built, existing geothermal plants operate at very low running cost (no fuel needed) — often $10–30/MWh operating cost. The high capital cost of drilling (wells cost $5–15 million each and can fail) is the primary economic risk. Source: Lazard LCOE Analysis 2024 · IRENA 2023.
Source: Lazard LCOE 2024 · IRENA Renewable Power Generation Costs 2023
What is EGS and why does it matter?
Enhanced Geothermal Systems (EGS) create artificial reservoirs in hot dry rock by hydraulically fracturing the rock and circulating water through it. This matters because it could make geothermal energy available anywhere on Earth — not just near volcanoes. The USA, China, Europe, India, and Australia all have abundant hot dry rock resources accessible at 3–10 km depth. The US DOE estimates EGS could provide over 100 GW of firm baseload power in the USA alone. Fervo Energy's Project Red (Utah, 2023) was the first commercial EGS plant to deliver power to the US grid. Source: US DOE FORGE · Fervo Energy.
Source: US Department of Energy FORGE programme · Fervo Energy · IEA
Cluster 10 · Connected pages
Explore further
Source register
Every source used on this page
Primary sources
IRENAGeothermal Power 2023 · Renewable Capacity Statistics 2024irena.org/geothermal-power
IEAWorld Energy Outlook 2024 · Geothermal market dataiea.org/weo-2024
ThinkGeoEnergyGlobal Geothermal Power Output 2024 · Plant database · Annual reviewthinkgeoenergy.com
WRI GPPDGlobal Power Plant Database · GPS coordinates · CC BY 4.0datasets.wri.org/globalpowerplantdatabase
LazardLevelised Cost of Energy Analysis 2024lazard.com/lcoe-2024
IPCC AR6Lifecycle emissions · Geothermal 38 g CO₂/kWhipcc.ch/report/ar6
US DOE FORGEFrontier Observatory for Research in Geothermal Energy · EGS researchenergy.gov/eere/forge
KenGenAnnual Report 2023 · Kenya geothermal capacitykengen.co.ke
Enel Green PowerAnnual Report 2023 · Larderello operationsenelgreenpower.com
Ormat TechnologiesORC binary cycle technology · Global installationsormat.com