Mazama Energy Raises $135 Million to Scale the World's Hottest Engineered Geothermal System - The Source

Mazama Energy announced $135 million in new capital to accelerate superhot rock geothermal commercial development, including an oversubscribed Series B led by Centaurus Capital, founded by John Arnold, and Doerr Capital. ConocoPhillips and Shell Ventures joined the round, with repeat investment from Khosla Ventures and Gates Frontier. Additional investors include SiteGround Capital, H. Barton Asset Management, and Jeffrey and Marieke Rothschild Foundation.

Mazama holds the record for the hottest engineered geothermal system ever built. In 2025 at Newberry, Oregon, Mazama created an engineered geothermal system at 629°F (331°C), proving reservoir creation, connectivity and heat recovery.

Mazama is now pushing toward even hotter targets. Its second well, Project Athena, reached that same 10,350-foot depth in 15 days this month, about 80% faster than the 2025 well, and is drilling a mile further down toward 750°F (400°C).

Reaching 750°F (400°C) delivers up to 10 times the power of a conventional 390°F (200°C) well, owing to the much higher energy density of supercritical water and improved reservoir productivity. This allows Mazama to deliver projects using 75% less water and drilling 80% fewer wells than conventional geothermal developments. Mazama’s technology has the potential to significantly improve the viability and permitting prospects of geothermal projects across a wide range of regions, reducing both surface infrastructure requirements and overall project footprint.

Unlocking superhot rock geothermal requires solving three interconnected challenges: reaching extreme temperatures without compromising the equipment, creating a productive reservoir where none exists naturally, and efficiently extracting heat to generate and sustain power. Mazama has spent the last several years developing these capabilities into a single integrated system paving the way towards delivering carbon-free, baseload power competitive with fossil fuels.

“The breakthrough in superhot geothermal is turning extreme heat into a repeatable, economic power system,” said Sriram Vasantharajan, CEO of Mazama Energy. “At Newberry, we have demonstrated the critical pieces together: extreme-temperature drilling, engineered reservoir creation and heat harvesting, at temperatures no other EGS has achieved. We are now driving that integrated system toward greater speed, efficiency and scale. That is the foundation for commercial superhot power.”

What this capital funds next

Utilities and grid planners are trying to add power they can count on around the clock faster than new transmission and new generation can be permitted and built. Mazama’s bet is to go down, not out: pull more energy from underground instead of adding more infrastructure above ground.

This financing funds Project Ceres, supported by the U.S. Department of Energy, which will advance horizontal well development in superhot rock toward a 15 MWe of capacity per well and demonstrate power generation in 2027. Athena and Ceres are the near-term proof points for a much larger ambition: Mazama is targeting independent certification of more than 10 GWe of resource potential at Newberry alone, while evaluating additional sites in the United States and internationally as it builds toward multi gigawatt-scale developments. Mazama’s goal is to make superhot rock geothermal a scalable source of firm power to address rising electricity demand, affordability and energy security around the world.

This story is based on submitted information and has not been verified by our news team.