“Superhot” Geothermal Startup Mazama Raises $135 Million

Geothermal energy developer Mazama Energy announced it has raised $135 million in a Series B funding round, with the proceeds aimed at accelerating the commercial development of its superhot rock geothermal technology.

The funding comes capital is being increasingly driven towards geothermal energy companies, most notably Fervo Energy’s recent $1.9 billion IPO, as as utilities and grid planners look to access round the clock, clean power faster than new transmission and new generation can be permitted and built.

Texas-based Mazama develops enhanced geothermal systems (EGS) designed to extract heat from superhot rock to generate utility-scale, carbon-free baseload power. The company integrates drilling, reservoir development, diagnostics and heat-harvesting technologies to develop and scale superhot rock geothermal systems.

The company holds the record for the hottest engineered geothermal system (EGS) ever built, after creating an engineered geothermal system at 629°F (331°C) at a well in Newberry, Oregon in 2025. The company said that it is currently drilling its second well, Project Athena, a mile further down toward temperatures of 750°F (400°C).

According to Mazama, reaching 750°F (400°C) delivers up to 10 times the power of a conventional 390°F (200°C) well, due to the much higher energy density of supercritical water and improved reservoir productivity. The company said that its technology enables it to deliver projects using 75% less water and drilling 80% fewer wells than conventional geothermal developments, as well as reducing both surface infrastructure requirements and the overall project footprint.

Mazama said that it plans to obtain independent certification of more than 10 GWe of resource potential at Newberry and is also evaluating additional sites in the U.S. and internationally as it works toward multi-gigawatt-scale developments.

Sriram Vasantharajan, CEO of Mazama Energy, said:

“At Newberry, we have demonstrated the critical pieces together: extreme-temperature drilling, reservoir creation and heat harvesting, at temperatures no other engineered geothermal system has achieved. We are now driving that integrated system toward greater speed, efficiency and scale. That is the foundation for commercial superhot power.”

The company said that the new capital will be used to fund Project Ceres, supported by the U.S. Department of Energy, which will advance horizontal well development in superhot rock toward 15 MWe of capacity per well and demonstrate power generation in 2027.

The Series B round was led by Centaurus Capital and Doerr Capital, with participation from ConocoPhillips, Shell Ventures, SiteGround Capital, H. Barton Asset Management, and the Jeffrey and Marieke Rothschild Foundation, alongside repeat investors Khosla Ventures and Gates Frontier.

John Doerr, Chairman of Doerr Capital and Kleiner Perkins, said:

“The world needs vastly more electricity, and we need to produce it cleanly and affordably. Superhot geothermal has the potential to be a major new source of 24/7 clean power, delivering dramatically more energy with less land, water, and infrastructure. Mazama is making that promise real and moving this technology decisively toward commercial scale.”