Quaise Energy closes $180M Series B to commercialize superhot geothermal

Why it matters

Nabors is putting $35 million and a strategic drilling framework behind Quaise's difficult scale-up from a field test of more than 100 meters to commercial wells measured in kilometers. The financing buys Quaise more time and industrial capacity, while the central technical questions remain depth, well durability and economical power production.

Carlos Araque, co-founder and CEO of Quaise Energy, has closed a $180 million Series B for the Houston-based MIT spinout he co-founded to drill for superhot geothermal resources with millimeter waves.

The final close includes a $35 million investment from Nabors Industries and a strategic drilling framework for future geothermal projects. The round brings Quaise's reported total funding to $280 million and is intended to move its drilling system toward commercial revenue and Project Obsidian in Central Oregon.

The final close follows the $134 million first close announced on July 7. Prelude Ventures led the first close, with strategic investments from JERA and Idemitsu Kosan and participation from nearly all existing backers, including Safar Partners. BofA Securities and Goldman Sachs & Co. LLC advised on the fundraise. Quaise has not disclosed its valuation.

An oilfield engineer's geothermal wager

Araque spent nearly 15 years developing downhole drilling technology at Schlumberger before joining The Engine, MIT's hard-tech investment platform, as its founding technical director. There he encountered research by Paul Woskov, an MIT Plasma Science and Fusion Center engineer who had adapted gyrotrons used in fusion research to melt and vaporize rock.

Araque founded Quaise in 2018 with Matt Houde and Aaron Mandell to commercialize that work. According to a Quaise profile of Houde, he had worked at geothermal developer AltaRock Energy and written proposals supporting MIT's millimeter-wave drilling research before joining Quaise.

Their plan joined two mature industrial toolkits. Gyrotrons could supply high-powered electromagnetic energy from the surface, while oilfield rigs, crews and supply chains could handle the rest of the well. Araque has described his years inside oil and gas as technical preparation and motivation to work on a cleaner power source.

In the July financing announcement, Araque said the round would take Quaise from field-proven technology to first commercial revenues.

That announcement described the $134 million first close as the initial equity component of a capital program that also involves project-level equity and debt. The distinction matters for a first-of-a-kind power plant: corporate funding supports Quaise and its technology program, while project financing would cover development and construction at specific sites.

Nabors is buying into the execution

Quaise said the $35 million investment builds on an existing relationship with Nabors.

The strategic framework covers drilling operations, system integration, rig engineering, automation and possible global project development. Under the Quaise agreement, Quaise will receive access to a dedicated land rig and an advanced platform integrating reservoir modeling, well design and drilling strategy.

Nabors has two routes to a return. Its equity investment provides exposure to Quaise, while the strategic drilling arrangement positions Nabors to sell rigs and services into future projects. The arrangement also ties Quaise closely to one contractor as it works through a drilling process with little commercial field history.

Quaise gains a partner accustomed to deploying heavy equipment, managing wells and shortening drilling programs through repeated field work. Those capabilities are difficult for a venture-backed hardware startup to build internally. The partnership follows Araque's original strategy of adapting oil-industry assets and labor instead of constructing a new industrial base from scratch.

JERA and Idemitsu bring a different set of incentives. In its July investment announcement, JERA said it would explore participation in geothermal feasibility studies and project development in Japan and overseas, along with possible collaboration using Quaise's geothermal-development and drilling expertise. That language stops short of committing JERA to a Quaise deployment in Japan.

From a field test to 20-kilometer targets

Quaise's drilling system uses a surface gyrotron to generate millimeter waves, which travel down standard metal tubing that acts as a waveguide. The beam heats and breaks up rock without placing a mechanical drill bit at the bottom of the hole. Purge gas carries the resulting particles back to the surface.

In July 2025, Quaise drilled more than 100 meters through granite in field conditions, according to an MIT Energy Initiative account of the program.

A commercial well requires a much longer chain of proof. Quaise must transmit energy efficiently over kilometers, remove material from a deep borehole, maintain well integrity under extreme heat and pressure, circulate fluid through the reservoir and sustain useful heat production.

Araque identified some of the industrial bottlenecks in April 16 testimony to a US House subcommittee. He said the gyrotron supply chain remains underdeveloped because the machines have historically served fusion research and a limited set of industrial uses. He also identified permitting and grid interconnection as time-consuming constraints for geothermal projects.

Project Obsidian is designed to begin with 50 MW of generation and scale to 250 MW as additional wells are developed, with commercial operation targeted by 2030. Quaise ultimately envisions gigawatt-scale development at the Oregon site, though later phases depend on the technical and economic performance of the initial wells.

Geothermal's capital race moves underground

Quaise's round arrives as investors place larger checks behind geothermal developers promising round-the-clock electricity. Fervo Energy, which uses horizontal drilling and hydraulic stimulation rather than millimeter waves, raised a $462 million Series E in December 2025 to support Cape Station, a Utah project designed to reach 500 MW.

The 2025 US Geothermal Market Report, published by the Department of Energy's National Laboratory of the Rockies and Geothermal Rising, compared financing for next-generation geothermal developers including Fervo, Eavor Technologies, Sage Geosystems, XGS Energy and GreenFire Energy. Their methods differ: some stimulate reservoirs, while others use closed-loop or pressurized-fluid systems. Quaise proposes replacing the mechanical drill bit with energy transmitted from the surface.

Araque wants Quaise to reach rock at roughly 300 C to 500 C, where a well could extract more energy than lower-temperature geothermal systems. In its geographic modeling, Quaise projects subsurface temperatures to depths of 20 kilometers and argues that millimeter-wave drilling could expand access to superhot resources beyond conventional geothermal hotspots. Quaise has yet to demonstrate drilling at that depth or operate a commercial power plant.

The Series B gives Araque more capital, access to a dedicated rig and a drilling contractor with direct financial exposure to the outcome. The next evidence will come from depth, fluid flow, well durability and power delivered to the grid.