Geothermal startup Mazama Energy has raised $135 million in an oversubscribed Series B funding round, the company said Thursday.
The round was led by Centaurus Capital and Doerr Capital, with participation from ConocoPhillips and Shell Ventures. Existing backers Khosla Ventures and Gates Frontier also participated. New investors SiteGround Capital, H. Barton Asset Management, and the Jeffrey and Marieke Rothschild Foundation joined the round.
Mazama was incubated at Khosla Ventures.
According to TechCrunch, the new funding will allow the company to develop horizontal wells in superhot rock capable of generating 15 megawatts of electricity per well. Mazama plans to begin producing electricity sometime next year. The company said its first site in Oregon has the potential to produce 10 gigawatts of electricity.
READ: Fed raises interest rates for first time in 3 years: Why Americans could feel the impact (September 17, 2026)
According to The Tech Buzz, the funding round is one of the largest investments in enhanced geothermal systems this year. Unlike traditional geothermal projects, which drill into existing hot springs or steam vents, Mazama is drilling about three miles into superhot rock formations. At those depths, temperatures can exceed 400 degrees Celsius, allowing the company to generate steam by pumping water into the rock and bringing it back to the surface.
The funding comes as technology companies such as Microsoft and Amazon seek carbon-free electricity to power expanding data centers and AI operations. Geothermal energy can provide continuous power without the intermittency associated with some traditional renewable energy sources.
Mazama is not alone in the space. Other companies, including Fervo Energy, have signed deals with Google to provide geothermal power for data centers. Sage Geosystems is also developing similar superhot-rock projects in Texas.
Mazama said in a news release that it holds the record for the hottest engineered geothermal system (EGS) ever built. In 2025, at its Newberry, Oregon, site, the company created an engineered geothermal system operating at 629 degrees Fahrenheit (331 degrees Celsius), demonstrating reservoir creation, connectivity and heat recovery.
READ: Kastle raises $24 million Series A for banking AI (September 17, 2026)
“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, 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.”
“Power is the constraint on everything we’re trying to build this decade,” said Vinod Khosla, founder of Khosla Ventures.
“We backed Mazama early because geothermal can be the planet’s largest source of clean, 24/7 power, and we’ve watched them build the world’s hottest engineered geothermal system. Scaling toward 400°C means ten times the heat from a fifth of the wells and a fraction of the water, the kind of breakthrough that makes geothermal a pillar of the energy transition.”