Mazama Energy announced Thursday that it has raised $135 million in an oversubscribed Series B round to accelerate development of enhanced geothermal systems targeting super-hot rock formations.

The funding will support the company's efforts to drill horizontal wells into deep, high-temperature rock layers capable of generating up to 15 megawatts of electricity per well. Mazama projects its first Oregon site could eventually produce 10 gigawatts of electricity, a significant increase from its earlier estimate of 5 gigawatts cited by investor Vinod Khosla. The company aims to begin electricity generation by next year and complete development of the site by 2030, targeting 200 megawatts of output.

Enhanced geothermal startups are emerging as potential alternatives to natural gas for powering energy-intensive AI data centers and other large-scale infrastructure. Unlike conventional geothermal systems, Mazama's approach focuses on accessing deeper, hotter rock formations where temperatures reach approximately 750°F (400°C). At these depths, water can be converted into a supercritical fluid under high pressure, enabling more efficient energy extraction than traditional steam-based methods.

Industry estimates suggest that tapping just 1% of the world's super-hot rock resources could yield over 63 terawatts of electricity, according to research from the University of Twente and the Clean Air Task Force. Mazama has already secured land for a second development site while advancing its initial project, reflecting growing confidence in the technology's scalability and commercial viability.

The funding round was led by Centaurus Capital and Doerr Capital, with participation from ConocoPhillips, Shell Ventures, and existing investors including Khosla Ventures and Gates Frontier. New participants such as SiteGround Capital, H. Barton Asset Management, and the Jeffrey and Marieke Rothschild Foundation also joined. Mazama was originally incubated at Khosla Ventures.

Tim De Chant, senior climate reporter at TechCrunch, has covered energy and environmental technology for publications including Wired, the Chicago Tribune, and Ars Technica. A lecturer at MIT's Graduate Program in Science Writing and former Knight Science Journalism Fellow, De Chant holds a PhD in environmental science, policy, and management from UC Berkeley and a BA from St. Olaf College.