Houston geothermal startup bumps Series B to $180M with Nabors investment

fresh funding

Quaise Energy received a boost to its Series B round. Photo courtesy Quaise

Houston-based geothermal startup Quaise Energy has closed its Series B fundraising round at $180 million after inking a significant investment from another local energy leader.

Quaise, which is developing a 50-megawatt superhot geothermal plant in Oregon, announced a "first close" of the round last month at $134 million, led by San Francisco-based investment firm Prelude Ventures. The $46 million bump has been fueled by a $35 million investment from Houston-based Nabors Industries.

The funding will go toward the continued development of the company's superhot geothermal plant, Project Obsidian, as well as the commercialization of Quaise's millimeter-wave drilling system, according to a news release.

“We are unlocking the most powerful clean energy source on Earth, and the Series B signals deep conviction across a wide range of investors,” Carlos Araque, Quaise CEO and president, said in the release. “Nabors is an invaluable partner as we move millimeter wave drilling to full commercial operations at Project Obsidian and beyond.”

Nabors, a repeat investor in Quaise, has also entered into a strategic framework agreement with Quaise. Under the agreement, Quaise will have access to a dedicated Nabors land rig and drilling platform. Nabors will also provide expertise in reservoir modeling, well design and drilling strategy.

Last year, Quaise drilled to a depth of about 330 feet using its millimeter-wave technology at its field site in Central Texas. Canary Media previously reported that Quaise plans to drill to nearly 3,300 feet later this year and to deploy its millimeter-wave technology at its power plant in 2027. The plant is expected to deliver power to the Pacific Northwest in 2030.

Quaise and Nabors say the partnership will improve drilling performance, reduce costs and accelerate project timelines.

“Superhot geothermal has the potential to make clean energy ubiquitous. That is why we are excited about our close relationship with Quaise,” Anthony Petrello, president and CEO of Nabors, added in the release. “Quaise’s millimeter wave technology changes the equation entirely by reaching superhot rock at temperatures and depths that are inaccessible with conventional drilling, transforming geothermal from a location-dependent resource into a global energy solution. Combined with Nabors’ drilling expertise and infrastructure, we see a path to gigawatt-scale geothermal power that no other company can offer today.”

Quaise reports that with the latest funding, it has now raised $280 million. It raised $21 million in a Series A1 financing round in 2024 and a $52 million Series A in 2022.

The company announced in March that it was aiming to raise $200 million for Project Obsidian through $100 million in Series B funding, plus an additional $100 million from grants, debt and project-level finance.

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A rendering of a Quaise Energy geothermal plant. Rendering via quaise.com

Houston cleantech startup secures $134M to develop ‘superhot’ geothermal plant

deep round

Houston-based Quaise Energy, a producer of utility-scale geothermal power, raised $134 million in a Series B round to advance its “superhot” geothermal power plant.

Climate-focused San Francisco-based investment firm Prelude Ventures led the round, with participation from JERA Co., Japan’s largest power generation company, and Idemitsu Kosan, one of Japan’s largest energy companies. Nearly all existing investors, including cleantech-focused investment firm Safar Partners, participated in the round.

“We have backed Quaise since the beginning because we believed accessing superhot rock would unlock geothermal energy at a scale the world has never seen,” Mark Cupta, managing director at Prelude Ventures, said in a press release.

The startup expects more equity and debt deals to close “imminently.” Quaise has raised $230 million since its founding in 2018.

Quaise says some of the fresh funding will go toward building the world’s first commercial-scale “superhot” geothermal power plant —Project Obsidian in central Oregon. In addition, Quaise is earmarking money for continued development and commercialization of its millimeter-wave drilling system toward depths exceeding 5 kilometers (about 16,400 feet).

Quaise uses a millimeter-wave drilling system developed at the Massachusetts Institute of Technology to remove rock at depths and temperatures that aren’t economically feasible with conventional drilling. With this technology, Quaise can reach rock at temperatures of around 570 degrees to 930 degrees in most places worldwide, enabling construction of geothermal systems that rival fossil fuels and nuclear energy in power density and that rival renewables in cost.

“Our ambition is to power civilization with Earth's most compelling energy source. This round takes us from field-proven technology to first commercial revenues,” Carlos Araque, co-founder, president and CEO of Quaise, added in the release.

Quaise has demonstrated the capability of its millimeter-wave drilling system at its Central Texas test site, drilling more than about 330 feet through granite in 2025—the first time the technology penetrated basement rock at full scale in the field. The company is approaching a depth of about 3,300 feet at the same site.

Construction of Project Obsidian is underway at Oregon’s Deschutes National Forest. The project, which has the potential to generate gigawatt-scale power, is slated to deliver electricity to the Pacific Northwest grid by 2030.

Quaise Energy is developing Project Obsidian, a superhot geothermal plant in central Oregon. Rendering via quaise.com.

Houston cleantech startup seeks $200M for superhot geothermal plant

seeing green

Houston-based Quaise Energy is looking to raise $200 million to support the development of a 50-megawatt superhot geothermal plant in Oregon.

The company is seeking $100 million in Series B funding, plus an additional $100 million from grants, debt and project-level finance, a representative from the company tells Energy Capital. Axios first reported the news late last month.

Quaise specializes in terawatt-scale geothermal power. It is known for its millimeter-wave drilling technology, which was developed at MIT.

The company's Project Obsidian development in central Oregon will combine conventional drilling with its millimeter-wave technology. Quaise says the project, targeted to come online in 2030, could be the first commercial plant to operate in superhot rock, a more efficient and abundant resource, but one that requires more advanced and durable drilling technology.

Quaise says Obsidian would initially generate 50 megawatts of "always-on" power and would be designed to add 200 megawatts as additional wells are developed. A power-purchase deal has already been signed for the initial 50 megawatts with an undisclosed customer.

A representative from the company says Quaise would also use the funding to continue advancing its millimeter-wave technology and prepare it for commercialization.

Last year, the company drilled to a depth of about 330 feet using its millimeter-wave technology at its field site in Central Texas.

“Our progress this year has exceeded all expectations,” Carlos Araque, CEO and president of Quaise Energy, said at the time. “We’re drilling faster and deeper at this point than anyone believed possible, proving that millimeter-wave technology is the only tool capable of reaching the superhot rock needed for next-generation geothermal power. We are opening up a path to a new energy frontier.”

Canary Media reports that Quaise plans to drill to nearly 3,300 feet later this year and to deploy its millimeter-wave technology at its power plant in 2027.

Quaise raised $21 million in a Series A1 financing round in 2024 and a $52 million Series A in 2022. Major investors include Prelude Ventures, Safar Partners, Mitsubishi Corporation, Nabors Industries, TechEnergy and others.

Quaise was one of eight Houston-area companies to appear on Time magazine and Statista’s list of America’s Top GreenTech Companies of 2025.

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Rice University spinouts named among 50 top cleantech companies to watch

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Two Rice University spinouts, Coflux Purification and DexMat, appear on a new list of the world’s 50 cleantech companies to watch.

Cleantech Group’s 2026 Cleantech 50 to Watch list recognizes early-stage companies “creating groundbreaking solutions to address some of the world’s most pressing environmental and sustainability challenges.”

Cleantech Group, a market research, consulting, and events company, selects the 50 honorees based on insights from analysts and early-stage innovators, along with public nominations.

Destroying “forever chemicals”

Coflux, founded in 2024, offers an onsite treatment system that captures and destroys manufactured “forever chemicals”—per- and polyfluoroalkyl substances—in water and wastewater. It’s a member of Greentown Houston.

Alec Ajnsztajn, CEO; Jeremy Daum, chief technology officer; and Dana Vazquez, chief commercial officer, co-founded Coflux. Ajnsztajn and Daum earned doctoral degrees from Rice, and Vazquez earned an MBA from the university.

Coflux spun out of Rice labs directed by professors Rafael Verduzco and Pulickel Ajayan.

Last year, Coflux received a $175,000 grant from the U.S. Food and Drug Administration’s National Institute of Food and Agriculture. The startup has also raised more than $500,000 in non-dilutive funding, including $80,000 awarded in 2024 by Rice’s One Small Step Grant program.

Promoting an alternative to copper

DexMat, founded in 2015, produces carbon nanotube products such as fibers, yarns, cables, and fabric. The company’s products address demand for materials that can reduce carbon emissions, according to CB Insights.

Its main product, Galvorn, is a copper alternative made of carbon nanotube fibers. CB Insights says Galvorn is engineered to be lighter and stronger than traditional conductive materials like carbon and steel. It’s used in industries such as energy, aerospace, defense, automotive, consumer electronics, and health care.

DexMat emerged from Matteo Pasquali’s Carbon Lab at Rice. Pasquali, co-founder of DexMat, co-invented the company’s technology with the late Nobel Prize-winning chemist Rick Smalley. Smalley was a professor of chemistry, physics, and astronomy at Rice.

Pasquali is a professor of chemical and biomolecular engineering, chemistry, materials science, and nanoengineering at Rice. He co-founded DexMat with Rice graduate Dmitri Tsentalovich, the company’s director of product innovation.

Earlier this year, DexMat raised $5 million in seed funding from Non Sibi Ventures, Governance Partners, Tailwind Futures, BetterWay, Capital Factory, and other investors. The company also secured $3 million in non-dilutive funding.

In 2023, DexMat raised $3 million in a pre-seed round led by Shell Ventures.

Stardust Power, Power Electronics expand to Houston and more top energy news

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Editor's note: October brings big updates for the energy transition sector, with two companies expanding to Houston and two more announcing major funding. Here are the five most-read stories published on EnergyCapital from September 30-October 15, 2026:

Lithium refiner expands into Houston with new Energy Corridor office

Battery-grade lithium carbonate manufacturer Stardust Power has expanded into Houston’s Energy Corridor, the company tells EnergyCapitalHTX. The company’s new office will serve as a project execution hub to support operations and planning for the company’s forthcoming lithium refinery in Muskogee, Oklahoma. The Greenwich, Connecticut-based, publicly traded company says the facility will be one of the largest lithium refining operations in the United States. The refinery is expected to have production capacity of up to 50,000 metric tons per year and seeks to address the critical shortage of U.S. lithium refining capacity. Continue reading.

Houston geothermal company picks Nevada site for commercial-scale project

Sage Geosystems, a Houston-based developer of geothermal power systems, has chosen a site in Nevada for its commercial-scale Project Vector facility. The company’s two-well enhanced geothermal system (EGS) will deliver around-the-clock geothermal heat to Ormat Technologies’ Blue Mountain geothermal power plant in Winnemucca, Nevada. The startup expects to begin drilling the first well later this year, with the first electricity to be generated in 2027 and full-scale production to start in 2028. Continue reading.

Houston carbon removal company secures $35M in financing

Houston-based Vaulted Deep, a waste management and carbon removal company, has announced a major $35 million debt facility from Italian investment bank Mediobanca to support its national expansion. U.K.-based market energy solutions CFP Energy arranged the deal, which is “the largest publicly disclosed U.S. commercial debt deal in durable carbon removal to be secured by long-term purchase contracts,” according to a news release from the companies. Continue reading.

Hertha Metals raises $133M Series A round, plans high-purity iron plant

Conroe-based Hertha Metals has closed a $133.65 million Series A round that includes a $65 million equity investment from the Pentagon. The startup uses a one-step process to convert iron into molten steel or high-purity iron. Khosla Ventures and Doerr Capital co-led the round, with participation from CEV, Pear Ventures, Gates Frontier, Niterra SUISO no MORI Fund, Toyota Ventures, and Siemens Financial Services. Continue reading.

European cleantech company breaks ground on Houston manufacturing site

Spanish renewable energy company Power Electronics broke ground on its new 53-acre Houston campus on Sept. 24. The new site is expected to create over 400 local jobs and deliver 40 gigawatts of production capacity per year. The company said that the campus is expected to be the largest manufacturing site for power conversion systems in the U.S. Power Electronics specializes in solar, energy storage, data centers and electrification technologies. Continue reading.

TotalEnergies expands solar joint venture with $1.2B portfolio in Texas, Ohio

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TotalEnergies, a French company whose U.S. headquarters is in Houston, announced this month that it is expanding its renewable energy joint venture with New York-based investment firm KKR by adding 700 megawatts of utility-scale solar projects.

The deal will add three utility-scale solar assets in Texas and Ohio, which are expected to reach commercial operation by Q1 2027, according to a news release from the company. The portfolio is valued at $1.2 billion.

The 50/50 joint venture between TotalEnergies and KKR currently holds 1.4 gigawatts of renewable energy and will grow to 2.1 gigawatts.

The new deal is expected to close this year. Once completed, TotalEnergies will operate the assets. The electricity generated from the solar projects will be sold to third parties, the company reports.

The companies originally formed the joint venture about a year ago when TotalEnergies sold KKR a 50 percent stake in a North American solar portfolio valued at $1.25 billion. The deal originally included six utility-scale solar assets, primarily located in the U.S.

“TotalEnergies is a renewable energy industry leader globally, and we are thrilled to establish this joint venture with the TotalEnergies team to support their renewables business," Cecilio Velasco, managing director KKR, said in a release last year. “We have long been investors in renewables through our infrastructure platform, having committed more than $23 billion to date in energy transition investments. TotalEnergies’ North American solar portfolio is a great fit for us, representing high-quality renewable energy assets with long term contracts.”

TotalEnergies reports that by June 2026 it held more than 37 gigawatts of gross renewable power generation capacity. It aims to achieve over 100 terawatt-hours of net electricity production by 2030.

The company signed a major power purchase agreement with Google earlier this year. Through the deal, TotalEnergies will supply the tech giant with 1 gigawatt of solar power for its data centers in Texas over a 15-year span.

However, the company also recently redirected nearly $1 billion in capital away from wind energy projects and "decided to renounce offshore wind development in the United States." Read more here.

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