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.