Mazama Energy has closed a $135 million Series B financing round to accelerate commercial development of superhot rock geothermal systems. The oversubscribed round was led by Centaurus Capital, founded by John Arnold, and Doerr Capital, with participation from ConocoPhillips and Shell Ventures. Repeat investors Khosla Ventures and Gates Frontier also joined the round alongside additional institutional backers.
A Record-Setting Technical Foundation
In 2025, Mazama Energy created the hottest engineered geothermal system ever built at Newberry, Oregon, reaching 629 degrees Fahrenheit (331 degrees Celsius). The project proved reservoir creation, connectivity, and heat recovery at temperatures no other engineered geothermal system has achieved. It also established the technical foundation for pushing toward even hotter targets with greater power potential.
Project Athena Shows Faster Execution
Mazama's second well, Project Athena, reached the same 10,350-foot depth in 15 days this month, about 80 percent faster than the 2025 well. The well is now drilling a mile further down toward a target of 750 degrees Fahrenheit (400 degrees Celsius). At that temperature, the energy density of supercritical water can unlock substantially more power from a single well.
Efficiency and Footprint Advantages
Reaching 750 degrees Fahrenheit delivers up to 10 times the power of a conventional 390-degree Fahrenheit well, according to the company. The higher energy density of supercritical water and improved reservoir productivity also allow projects to use 75 percent less water and drill 80 percent fewer wells than conventional geothermal developments. These advantages can reduce surface infrastructure, improve permitting prospects, and lower overall project footprints across a variety of regions.
Solving Three Interconnected Challenges
Unlocking superhot rock geothermal requires solving three interconnected challenges: reaching extreme temperatures without compromising equipment, creating a productive reservoir where none exists naturally, and efficiently extracting heat to generate and sustain power. Mazama has spent several years developing these capabilities into a single integrated system. The company says this work paves the way toward delivering carbon-free, baseload power that is competitive with fossil fuels.
CEO Sees Repeatable Economic Power System
Sriram Vasantharajan, chief executive officer of Mazama Energy, said the breakthrough is about turning extreme heat into a repeatable, economic power system. He said Newberry has demonstrated critical pieces together, including extreme-temperature drilling, reservoir creation, and heat harvesting at temperatures no other engineered geothermal system has achieved. The company is now driving that integrated system toward greater speed, efficiency, and scale as the foundation for commercial superhot power.
Funding Supports Project Ceres and Scale
The new capital will fund Project Ceres, supported by the U.S. Department of Energy, which will advance horizontal well development in superhot rock toward 15 megawatts of electric capacity per well and demonstrate power generation in 2027. Athena and Ceres are near-term proof points for a larger ambition that includes independent certification of more than 10 gigawatts of resource potential at Newberry alone. Mazama is also evaluating sites in the United States and internationally as it builds toward multi-gigawatt-scale developments.
Investors See Growing Need for Firm Clean Power
John Doerr, chairman of Doerr Capital and Kleiner Perkins, said the world needs vastly more electricity produced cleanly and affordably, and that superhot geothermal can become a major source of 24/7 clean power. Centaurus Capital President John Arnold noted that firm carbon-free power with a relatively small footprint requires significant technical innovation. Vinod Khosla, founder of Khosla Ventures, added that power is the constraint on everything being built this decade.
Mazama Energy's $135 million Series B reflects rising investor conviction that superhot rock geothermal can progress from technical records to commercial power generation. By pursuing higher temperatures with fewer wells and a smaller surface footprint, the company aims to address rising electricity demand, affordability, and energy security. Its planned 2027 power demonstration will be a critical test of whether superhot geothermal can scale as reliable, carbon-free baseload power.