Mazama Energy closed an oversubscribed $135 million Series B to scale superhot geothermal drilling at its Oregon site near Newberry Volcano, the Frisco, Texas–based company said Thursday.

The round was led by Centaurus Capital, the family office of billionaire John Arnold, and Doerr Capital. Oil and gas majors ConocoPhillips and Shell Ventures participated, alongside existing backers Khosla Ventures and Gates Frontier.

"Superhot rock is almost essential for geothermal to become cost-competitive with fossil fuels," Mazama CEO Sriram Vasantharajan told Canary Media ahead of the announcement.

What does Mazama plan to build first?

The new capital funds Project Ceres, a Department of Energy–backed initiative. It targets 15 megawatts of clean electricity capacity from a single horizontal well — a layout no enhanced system has demonstrated at commercial scale.

Mazama plans to start drilling later this year and begin system testing in early 2026. At 400°C, each well could deliver up to 10 times more power than a conventional 200°C well, according to the company.

"Ceres becomes our blueprint for our scalable, commercial pathway for deployment of superhot rock," Vasantharajan said.

What has Mazama already proven?

Mazama hit 331°C (629°F) at its Newberry pilot in October 2024, calling it the world's hottest enhanced geothermal system. The project drew a U.S. Department of Energy grant.

"This proof of concept opens the door to deeper and hotter opportunities at Newberry and beyond," said John McLennan of Utah Forge, a federally funded geothermal laboratory in Beaver County, Utah.

The first well reached 10,350 feet. The second matched that depth about 80% faster — a critical gain when rigs cost more than $100,000 a day to run. Mazama continues drilling thousands of feet deeper as it works toward a 400°C target.

Why are oil and gas names on the cap table?

Vasantharajan is a chemical engineer who came out of complex oil and gas wells, including deep-water and heavy-oil work. He launched Mazama in 2023 to commercialize drilling tools built for harsh downhole environments.

The investor mix — ConocoPhillips, Shell Ventures, and oil-and-gas-experienced founders — reflects that heritage. Arnold framed the bet around firm, dispatchable power.

"Superhot geothermal offers the promise of firm, carbon-free power with a relatively small footprint, but realizing that promise requires significant technical innovation," Arnold said in a release.

How does this differ from conventional geothermal?

Conventional plants tap natural hot-water reservoirs. Enhanced geothermal systems drill several miles into dry rock and fracture it to create artificial reservoirs — a method the industry says could unlock hundreds of gigawatts across the western U.S.

The hotter the rock, the fewer wells a developer needs per megawatt. That is the unit-economics case the Series B is meant to fund.

Who else is racing?

Three rivals moved in the same window:

• Fervo Energy went public earlier this year and signed a power-purchase agreement with Google for its Utah project.
• Sage Geosystems recently started producing power from its first pilot in Texas.
• Quaise Energy, also drilling near Newberry Volcano, closed a $180 million funding round last month.

What decides the next milestone?

Drilling must start on the horizontal section of Project Ceres later this year. The Department of Energy has now backed both the Newberry pilot and Project Ceres, anchoring the build-out in federal geothermal research dollars.

A successful demonstration of 15 MW from one well in early 2026 would be the first commercial-scale test of superhot rock in the U.S. — and the trigger for the next funding round across the sector.

Investors will watch two metrics first: the temperature reached in the horizontal leg and the time required to drill it.