Geothermal Companies: Who Actually Does What in 2026

By Geothermal Insider · Updated September 12, 2026

Type "geothermal companies" into a search box and the list you get back puts a plant operator at The Geysers next to a venture-backed startup that has not yet sold electricity from its flagship project, next to a heat pump factory in Oklahoma City, next to a contractor drilling a loop under somebody's lawn. All four get called geothermal companies. They sell different things to different customers, so confusing the categories distorts any comparison you try to make between them.

They fall into four categories, separated by what they sell, who buys it, and what they have built. Each capacity figure below carries the date it was measured.

Four Different Businesses Wearing One Label

The four categories differ in their products, their customers and their business models.

The scale gap between the first and third categories matters. The United States had 99 operating geothermal power plants as of 2024; the same market report estimates geothermal heat pumps in 1.27 million homes and 27,300 commercial buildings. A power producer has a handful of very large customers; a heat pump maker has a million small ones. A fifth group, the oil and gas service companies, drills for all of the above.

The Power Producers Who Own the Plants

U.S. installed geothermal nameplate capacity reached 3.97 GWe, or 3,969 MWe, as of 2024, across 99 plants, with California accounting for 2,868 MWe and Nevada 892 MWe. Globally, geothermal power capacity reached almost 15.4 GW at the end of 2024, after roughly 320 MW was commissioned that year. Against that backdrop, two companies, Ormat and Calpine, together accounted for 69% of installed U.S. capacity and 61% of operating plants in 2024. For what these companies actually own, see our guide to how a geothermal power plant works.

Ormat Technologies

Ormat is the unusual case that does nearly everything: by its own SEC description it is a vertically integrated developer, equipment manufacturer, constructor, owner and operator of geothermal, recovered-energy and energy-storage plants. It trades on the NYSE as ORA. It is still buying and building. In June 2025 it completed an $88 million purchase of the 20 MW Blue Mountain plant from Cyrq Energy. Its second-quarter 2026 results, reported in August 2026, noted commercial operation of a 10 MW plant in Dominica in July 2026 and a 5 MW upgrade at Cove Fort completed in June 2026. In January 2026 it also co-led a funding round in Sage Geosystems, a next-generation developer.

Ormat's published portfolio figure combines geothermal and solar capacity, so it does not yield a geothermal-only comparison. What is clear is that Ormat and Calpine together held 69% of installed U.S. geothermal capacity in 2024.

Calpine, now part of Constellation

Calpine is the other half of that 69%, and a very different animal: a concentrated conventional hydrothermal operator rather than an equipment maker. Its company page says it operates 13 plants at The Geysers in California with capacity of up to 725 MW (page undated; accessed September 2026) — but treat that as a floor rather than a current figure: Calpine's own Geysers site announces a completed 25 MW expansion, 18 MW of it contracted to Clean Power Alliance and 7 MW already serving MCE, and an SEC filing has described the fleet at 732 MW. Its February 2026 plant table lists the individual Geysers units, including McCabe at 85 MW, Ridge Line at 77 MW, Eagle Rock at 71 MW and Calistoga at 69 MW.

The ownership changed this year. On January 7, 2026, Constellation completed its acquisition of Calpine from Energy Capital Partners, making Calpine a wholly owned subsidiary. Any list still showing a standalone Calpine ticker, or naming Energy Capital Partners as the owner, is stale. The public parent is Constellation Energy Corporation, Nasdaq: CEG.

BHE Renewables, operating as CalEnergy

BHE Renewables is part of Berkshire Hathaway Energy and is not separately listed. Its geothermal business operates as CalEnergy and owns 10 geothermal facilities in California's Imperial Valley with total net capacity of 345 MW, per an April 2025 fact sheet. It is also testing direct lithium extraction from geothermal brine through a joint venture with Occidental while continuing to generate electricity from the same brine.

Cyrq Energy

Cyrq is the seller in the Blue Mountain deal. It says it retained Hudson Ranch, Soda Lake, Patua and Thermo and would redirect more activity toward project development. Its plant page, which carries no measurement date, reports Hudson Ranch at 49.8 MW, Soda Lake at 26.5 MW, Patua at 48 MW of geothermal plus 10 MWac of solar, and Thermo at 14.5 MW. Cyrq publishes no total, and those individual nameplate figures should not be treated as a current net-output sum. It is organized as Cyrq Energy, LLC; its beneficial owners are not identified on its company pages.

Terra-Gen

Terra-Gen develops, owns and operates utility-scale renewable projects, and reports an undated 4.2 GW of wind, solar and battery projects with no geothermal-only total. It has been owned 50/50 by Masdar and Igneo Infrastructure Partners since October 2024, when Energy Capital Partners exited.

Pertamina Geothermal Energy and Energy Development Corporation

The two largest names outside the United States are in Indonesia and the Philippines. Pertamina Geothermal Energy (PGE) reports 727 MW directly operated and another 1,205 MW managed under Joint Operating Contracts, for 1,932 MW across its working areas, on a company page citing its 2025 Sustainability Report; PGE documented the same 1,932/727/1,205 split in a disclosure dated June 3, 2026. It trades on the Indonesia Stock Exchange as IDX: PGEO.

Energy Development Corporation (EDC) in the Philippines produces steam and generates and sells electricity. Its May 2024 offer supplement reported 1,169 MW of geothermal capacity within a 1,463 MW renewable portfolio as of March 31, 2024. Its current homepage reports only a total renewable figure of 1,388.8 MW, not a geothermal-only number, so the 1,169 MW should be read as a March 2024 snapshot, not today's capacity.

Who Is the Biggest Geothermal Company

It depends on what you measure. By capacity managed inside its geothermal working areas, including the partner-owned Joint Operating Contracts, PGE reports the largest figure at 1,932 MW. But that is not capacity PGE owns and runs itself; its directly operated figure is 727 MW — and on that basis Kenya's KenGen, which reported 754 MW of its own geothermal capacity in September 2026, is larger. The ranking flips depending on whether you count what a company operates or what it manages. EDC's homepage calls it the world's largest vertically integrated geothermal company; its most recent geothermal-only disclosure gives 1,169 MW as of March 31, 2024. Ormat's published portfolio figure mixes geothermal with solar, leaving no comparable current number. Within the United States the picture is simpler: Ormat and Calpine together held 69% of installed capacity in 2024, and Calpine's Geysers fleet alone is up to 725 MW by its own count.

PGE's reported managed capacity also moves between documents: its release for the fiscal 2024 annual general meeting gives 1,887 MW managed (672 MW direct plus 1,205 MW with partners), while the later page citing its 2025 Sustainability Report gives 1,932 MW (727 MW direct plus 1,205 MW under JOCs). The two figures cover different reporting periods.

So PGE leads by managed working-area capacity, and no current, apples-to-apples source establishes the largest company by net geothermal ownership alone. Anyone who says flatly that "X is the largest geothermal company" is picking a yardstick without telling you which one.

What the Next Generation Has Actually Built

The second category is where most of the headlines come from: companies trying to make geothermal work where there is no natural steam reservoir, whether by engineering fractures in hot rock, running sealed pipes through it, or drilling deeper and hotter than anyone has before. The technology is explained in our piece on enhanced geothermal systems, and the DOE field laboratory behind much of the public data is covered in our guide to Utah FORGE. What separates them in practice is what each has physically built and whether it is selling electricity yet.

Fervo frames the whole category. It completed an IPO in May 2026 and trades on Nasdaq as FRVO; the offering of 80.5 million shares at $27 produced approximately $2.2 billion in gross proceeds. Its August 2026 quarterly report still described its flagship Cape Station Phase I as commissioning toward first power in the fourth quarter of 2026. A company can be worth billions and not yet be selling a kilowatt-hour from the project it was valued on. That is not a criticism; it is what a development-stage power company looks like.

Sage reports that SMECI showed water losses below 10% across multiple cycles, which goes directly at one of the longest-running objections to engineered reservoirs. Its first larger commercial project is planned at an existing Ormat plant in Nevada for completion in 2027, which is also why Ormat co-led its funding round. Our Sage Geosystems profile goes deeper.

Eavor is the clearest example of a closed-loop system feeding a grid, and in May 2026 it published an unusually candid technical update: cement-related hydraulic communication compromised five of six lateral pairs at Geretsried; three were flushed successfully, and four lateral pairs were operating as expected. Its capacity has been described three ways: the 2022 groundbreaking announcement cited 9 MWe, a 2023 media kit gave approximately 8.2 MWe, and the May 2026 technical update describes operation on only a partially completed first loop. Those are design-versus-built differences, not interchangeable figures. See our Eavor guide, and our profiles of XGS Energy, Quaise Energy and Fervo Energy stock, explained.

Who Is Public and Who Is Still Private

The next-generation category runs on venture and project capital, and the amounts get reported as if they were revenue. They are not. What has actually been disclosed:

• Fervo reported $368.3 million of Series D preferred-stock gross proceeds from 2024 and $462.0 million of Series E gross proceeds from 2025 in its pre-IPO filing, then raised approximately $2.2 billion gross in the May 2026 IPO. Separately, it closed $421.4 million of non-recourse project financing for Cape Station Phase I, led by Barclays, BBVA, HSBC, MUFG and Société Générale.
• Sage closed over $97 million of Series B funding in January 2026, co-led by Ormat and Carbon Direct Capital, with participants including Nabors, SiteGround Capital and UC Berkeley Foundation's Climate Solutions Fund.
• Quaise completed a $180 million Series B, taking total funding to $280 million as of September 2026. The round included Prelude Ventures, JERA, Idemitsu, Safar Partners and a $35 million investment from Nabors, which became its largest shareholder at 14% fully diluted.
• XGS reported over $40 million raised by May 2024 and later raised $13 million in March 2025 from Aligned Climate Capital, ClearSky, ClimateIC and WovenEarth Ventures. It has not published a new cumulative total.
• Eavor has disclosed a C$90 million Canada Growth Fund investment, a €91.6 million EU Innovation Fund grant and €130 million of Geretsried debt financing. Eavor has not published a cumulative funding total.
• Mazama says it was incubated and backed by Khosla Ventures and is backed by Gates Frontier; no cumulative total is published.
• Dandelion (an installer, covered below) disclosed a $70 million Series B1 completed in 2022 and a $40 million Series C in September 2024 led by GV.

The publicly traded geothermal-related companies are Ormat, NYSE: ORA; Fervo, Nasdaq: FRVO; Constellation (owner of Calpine), Nasdaq: CEG; Pertamina Geothermal Energy, IDX: PGEO; Trane Technologies, NYSE: TT; Baker Hughes, Nasdaq: BKR; and Nabors, NYSE: NBR. Sage, XGS, Eavor, Quaise, Mazama, AltaRock, Cyrq, Terra-Gen and Dandelion have no confirmed public listing. Carrier trades as NYSE: CARR, and Berkshire Hathaway as NYSE: BRK.A and BRK.B. SLB trades as NYSE: SLB and Helmerich & Payne as NYSE: HP.

The buyable names, the ETF question and the stale tickers that still circulate are covered in geothermal stocks and investing.

The Manufacturers Behind the Box in Your Basement

The third category makes the geothermal heat pump: the unit in a basement or mechanical room that moves heat between the building and a ground loop. These companies have nothing to do with power plants.

WaterFurnace and ClimateMaster, the two brands people most often cross-shop against each other, are both owned by the same Swedish parent, NIBE. WaterFurnace, which manufactures residential and commercial geothermal and water-source heat pumps, was acquired by NIBE in 2014 and now serves as NIBE's North American Energy-business headquarters. ClimateMaster is a subsidiary of Climate Control Group, which NIBE purchased from LSB Industries for $364 million in 2016; any document still calling ClimateMaster an LSB company is out of date. ClimateMaster reports a 510,000-square-foot plant in Oklahoma City and over 600 jobs.

NIBE's reach goes further. It acquired 10% of Enertech Global in 2011 and the remaining 90% in 2014; Enertech's portfolio consisted mainly of geothermal heat pumps. GeoStar, still an active residential and commercial brand, is identified in WaterFurnace acquisition materials as a WaterFurnace brand. So four names on the showroom floor trace back to one owner. NIBE is listed on Nasdaq Stockholm. WaterFurnace's old Toronto listings, WFI and WFI.U, are stale: NIBE acquired all outstanding shares in 2014.

The rest of the field: Bosch sells geothermal HVAC within the privately controlled Bosch Group, where Robert Bosch Stiftung holds roughly 94% of Robert Bosch GmbH's capital. Carrier currently markets packaged, split and water-to-water residential geothermal heat pumps under the Carrier name. Trane offers commercial geothermal heat-pump systems and is a brand of publicly traded Trane Technologies, NYSE: TT.

Which of these belongs in a particular house is a question of capacity, efficiency and dealer support, compared brand by brand in the geothermal heat pump brand comparison.

The Installers

The fourth category is the one a homeowner actually signs a contract with: the installer designs the system, drills or trenches the ground loop, sets the heat pump, and increasingly arranges the financing. The manufacturer's name is on the box; the installer's name is on the invoice.

Dandelion Energy combines ground-loop drilling, system design, heat-pump supply, installation and financing rather than acting solely as an HVAC company. It says it installed thousands of residential systems and more than 1 million linear feet of ground loops from 2017 through October 2025, and in October 2025 it launched a lease program that separates ownership of the equipment from the homeowner, a structure more commonly associated with rooftop solar.

Where you can hire it is less simple than its marketing suggests. Its contact page says it is "available across the U.S." and lists facilities in Virginia, Massachusetts, New York and Colorado. Its retrofit leasing, however, was specifically available in New York and Connecticut, while its builder leasing program was launching in 16 incentive-rich states including Maryland and New Jersey. Availability therefore depends on the product and the project type, address by address — see the Dandelion Energy review.

Few other U.S. residential installers publish scale and funding figures comparable to Dandelion's. Dandelion is the prominent venture-backed national name; most other installers are local HVAC and drilling contractors that publish little about their scale, which is what makes choosing a geothermal installer a matter of asking the right questions directly.

The Oil and Gas Crossover

A geothermal well is a hole in hot rock, and the companies that know most about drilling holes in rock are oil and gas service companies. Several have geothermal businesses that fit none of the four categories: they do not own plants, make heat pumps or install systems. They drill, and increasingly they invest.

• SLB supplies geothermal exploration, drilling, completion, production-enhancement and workover services for conventional hydrothermal, next-generation, direct-use and heating-and-cooling projects.
• Baker Hughes (Nasdaq: BKR) supplies integrated geothermal technology and services and, in June 2026, partnered with EnCap-backed Mantle Reach Power on projects targeting up to 500 MW over five years.
• Nabors (NYSE: NBR) combines investment with field execution: rigs, drilling services, well construction, engineering and automation for partners including Sage, GA Drilling and Quaise. Its $35 million investment made it Quaise's largest shareholder at 14% fully diluted, a Nabors PACE-B rig was drilling at Quaise's Oregon Project Obsidian as of August 2026, and Nabors holds exclusivity for drilling services on Quaise projects.
• KCA Deutag served as drilling contractor for Eavor's first commercial Geretsried closed-loop project: a conventional drilling contractor doing the work without owning the plant. It has been owned by Helmerich & Payne (NYSE: HP) since January 2025 — the same H&P that is drilling at Fervo's Cape Station, where Fervo added a third H&P rig in August 2026, and that appears separately as an XGS investor. H&P appears in the sector as KCA Deutag's owner, a drilling contractor and an investor at the same time.

How to Tell Which Kind of Company You Are Looking At

When a name lands in front of you, four questions will place it.

1. Does it sell electricity to a grid today? If yes, and it owns the plants, it is a power producer. If it talks about "first power" as a future date, it is a developer, however large its valuation.
2. Is the product a plant or a box? A manufacturer's website shows heat pumps and dealer locators; a power company's shows megawatts. They never overlap.
3. Who is the customer? A utility or grid means power producer or developer. A homeowner means installer. An installer or dealer means manufacturer.
4. Does it own anything, or does it drill for those who do? Nabors, SLB, Baker Hughes and KCA Deutag show up in geothermal press releases constantly as service and investment crossovers, not owners of a resource.

One more check catches most stale information: when was the ownership last confirmed? Calpine changed hands in January 2026. ClimateMaster changed hands in 2016 and documents still get it wrong. WaterFurnace delisted in 2014 and its old tickers still circulate. Fervo went public in May 2026. A company list not checked this year is probably wrong about at least one of these.