Key takeaways
- Top pick: Fervo Energy, best for: Utilities and data centres buying firm clean power.
- Also near the top: Ormat Technologies, best for: Utilities and large buyers wanting proven geothermal supply; and Eavor Technologies, best for: Utilities and municipalities in regions without natural geothermal reservoirs.
- How it was ranked: 10 deep tech companies compared. Each verdict is below.
Best Geothermal Energy Companies: Top 10 Ranked. Fervo Energy ranks first, with a Lister Score of 97.5.
Fervo Energy leads next-generation geothermal globally, with the first enhanced geothermal plant in commercial operation, and Ormat is the most established geothermal power producer. Eavor is the most proven in closed-loop systems, while
Quaise Energy and
Mazama Energy lead the push into superhot rock.
Best Geothermal Energy Companies in 2026, compared| RANK | ENTRY | BEST FOR | SCORE | FROM |
|---|
| 1 |  Fervo EnergyFervo raised a $462 million Series E in December 2025. | Utilities and data centres buying firm clean power | 97.5 | Custom |
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| 2 |  Ormat TechnologiesOrmat reports a total generating portfolio of more than 1,800 MW, including geothermal, solar and energy storage. | Utilities and large buyers wanting proven geothermal supply | 96.2 | Custom |
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| 3 |  Eavor TechnologiesEavor's Geretsried project was awarded a 91.6 million euro grant from the EU Innovation Fund. | Utilities and municipalities in regions without natural geothermal reservoirs | 94.9 | Custom |
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| 4 |  Quaise EnergyQuaise closed a $180 million Series B in August 2026, including $35 million from Nabors Industries. | Utilities planning very high-output geothermal plants | 93.6 | Custom |
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| 5 |  Sage GeosystemsSage raised more than $97 million in a Series B round announced in January 2026. | Data centres and utilities wanting firm power with storage | 92.3 | Custom |
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| 6 |  Mazama EnergyMazama raised $135 million in a Series B led by Centaurus Capital and Doerr Capital in September 2026. | Large power buyers backing superhot geothermal | 91.0 | Custom |
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| 7 |  XGS EnergyXGS Energy and Meta announced a 150 MW geothermal partnership in New Mexico in June 2025. | Tech companies and utilities in dry regions | 89.6 | Custom |
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| 8 |  ZanskarZanskar raised $115 million in a Series C led by Spring Lane Capital, bringing its total equity to $180 million. | Utilities buying geothermal power in the western US | 88.2 | Custom |
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| 9 |  Geothermal Engineering Ltd (GEL)GEL signed a long-term agreement with Octopus Energy for at least 3 MW of United Downs output. | UK energy buyers wanting local geothermal power | 86.8 | Custom |
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| 10 |  Rodatherm EnergyRodatherm closed an oversubscribed $38 million Series A led by Evok Innovations. | Developers targeting hot sedimentary basins | 85.4 | Custom |
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How to choose
Start from what you need it for. Where each entry fits best:
Each entry's full verdict is below.
The ranking, in detail
01
Enhanced geothermal power
Fervo Energy, based in Houston, develops enhanced geothermal systems using horizontal drilling. Its Cape Station in Beaver County, Utah, sent first power to the grid on 24 September 2026 and declared commercial operation of its first 33 MW unit six days later.
PROS- Firm, always-on clean power
- Large contracted demand
CONS- First large plant just coming online
- Heavy capital spending
- Best for
- Utilities and data centres buying firm clean power
- Where it falls short
- It is not yet fully operational as its first large plant is just coming online.
- Pick something else if
- you need immediate power availability.
97.5
02
Geothermal power plants and equipment
Ormat Technologies, based in Reno, Nevada, builds and operates geothermal power plants in the US, Kenya, Guatemala, Indonesia and other markets, alongside solar and battery storage. In February 2026 it signed a power purchase agreement for up to 150 MW of geothermal capacity through NV Energy to support Google's data centres.
PROS- Decades of geothermal operating history
- Builds its own power plant equipment
CONS- Mostly conventional geothermal today
- Next-generation projects at an early stage
- Best for
- Utilities and large buyers wanting proven geothermal supply
- Where it falls short
- It relies mostly on conventional geothermal technology with next-generation projects still early.
- Pick something else if
- you need advanced next-generation geothermal solutions immediately.
96.2
03
Eavor-Loop closed-loop geothermal
Eavor Technologies, based in Calgary, develops the Eavor-Loop, a sealed closed-loop geothermal system that does not need a natural reservoir or fracking. Its project in Geretsried, Germany, delivered electricity to the grid on 4 December 2025.
PROS- Works without natural water reservoirs
- First closed-loop system to deliver grid power
CONS- Early output below planned site capacity
- First commercial site still ramping up
- Best for
- Utilities and municipalities in regions without natural geothermal reservoirs
- Where it falls short
- Early output falls below planned site capacity as the first commercial site is still ramping up.
- Pick something else if
- you need immediate full capacity.
94.9
04
Millimetre-wave drilling for superhot geothermal
Quaise Energy is developing millimetre-wave drilling to reach superhot rock. It plans a 50 MW plant near Newberry Volcano in Oregon, called Project Obsidian, which is targeted to come online by 2030.
PROS- Drilling method aimed at deeper, hotter rock
- Backed by drilling contractor Nabors
CONS- No power plant operating yet
- Drilling technology still being proven in the field
- Best for
- Utilities planning very high-output geothermal plants
- Where it falls short
- It has no power plant operating yet.
- Pick something else if
- you need immediate geothermal power generation.
93.6
05
Pressure geothermal power and energy storage
Sage Geosystems, based in Houston, develops pressure geothermal systems that provide both baseload power and energy storage. Its 3 MW EarthStore facility in Christine, Texas, is operating, and in August 2024 it agreed to supply Meta with up to 150 MW of geothermal power.
PROS- Combines power generation and storage
- Agreement with Meta for up to 150 MW
CONS- First power generation plant still in development
- Small operating site so far
- Best for
- Data centres and utilities wanting firm power with storage
- Where it falls short
- It has only a small operating site so far.
- Pick something else if
- you need immediate large-scale deployment.
92.3
06
Superhot rock enhanced geothermal
Mazama Energy is developing superhot enhanced geothermal systems at Newberry Volcano in Oregon, where it reached 331 degrees Celsius (629 degrees Fahrenheit) in October 2025, a record for an engineered geothermal system.
PROS- Record temperature for an engineered geothermal system
- Well funded for further drilling
CONS- Pilot stage
- No commercial power yet
- Best for
- Large power buyers backing superhot geothermal
- Where it falls short
- It has no commercial power yet.
- Pick something else if
- you need immediate commercial energy supply.
91.0
07
Water-independent closed-loop geothermal
XGS Energy develops a closed-loop geothermal system that does not depend on water from the reservoir. In June 2025 it agreed with Meta to develop a 150 MW advanced geothermal project in New Mexico.
PROS- Does not need reservoir water
- Agreement with Meta
CONS- First phase not yet operating
- Early commercial stage
- Best for
- Tech companies and utilities in dry regions
- Where it falls short
- The first phase is not yet operating.
- Pick something else if
- you need immediate operational capacity.
89.6
08
AI-driven geothermal discovery and development
Zanskar, based in Salt Lake City, uses AI to find hidden geothermal resources and develop power plants on them. It restored the Lightning Dock geothermal plant in New Mexico to full capacity.
PROS- AI exploration finds resources with no surface signs
- Already operates a power plant
CONS- Depends on finding natural reservoirs
- Most new plants still in development
- Best for
- Utilities buying geothermal power in the western US
- Where it falls short
- Most new plants are still in development.
- Pick something else if
- you need immediate operational capacity.
88.2
09
Deep geothermal power and lithium in the UK
Geothermal Engineering Ltd runs the United Downs plant in Cornwall, the UK's first deep geothermal power plant, which began delivering continuous power on 26 February 2026. The site also produces lithium from its geothermal brine.
PROS- First geothermal power plant in the UK
- Extra revenue from lithium
CONS- Small output so far
- Focused on UK sites
- Best for
- UK energy buyers wanting local geothermal power
- Where it falls short
- It is currently limited to UK sites.
- Pick something else if
- you need geothermal power outside the UK.
86.8
10
Waterless closed-loop geothermal
Rodatherm Energy, based in Calgary and Salt Lake City, has developed a fully cased, pressurised closed-loop geothermal system for hot sedimentary basins that uses a proprietary working fluid instead of water. Its first pilot module is planned in Utah.
PROS- Closed-loop design for sedimentary basins
- Does not consume water
CONS- Pilot stage
- No commercial power yet
- Best for
- Developers targeting hot sedimentary basins
- Where it falls short
- Pilot stage.
- Pick something else if
- you need immediate commercial power.
85.4
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Frequently asked questions
What are the best Geothermal Energy Companies?
Fervo Energy ranks first on Lister. Fervo Energy, based in Houston, develops enhanced geothermal systems using horizontal drilling. Its Cape Station in Beaver County, Utah, sent first power to the grid on 24 September 2026 and declared commercial operation of its first 33 MW unit six days later.
What are the top 10 Geothermal Energy Companies?
1. Fervo Energy; 2. Ormat Technologies; 3. Eavor Technologies; 4. Quaise Energy; 5. Sage Geosystems; 6. Mazama Energy; 7. XGS Energy; 8. Zanskar; 9. Geothermal Engineering Ltd (GEL); 10. Rodatherm Energy.
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