Geothermal startup Mazama Energy raised $135 million in an oversubscribed Series B round, the company announced Thursday. The funding will help the Khosla Ventures-incubated company develop horizontal wells in super-hot rocks capable of generating 15 megawatts of electricity per well — up to 10 times more than traditional geothermal technologies.
Mazama is drilling past 10,000 feet in 15 days on its way to approximately 15,000 feet deep. At those depths, the company accesses 750°F (400°C) heat, which at high pressures turns water into a "supercritical" fluid that absorbs far more energy than ordinary steam.
The company's first site in Oregon is now estimated at 10 gigawatts of capacity — a sharp upward revision from the 5 GW projection investor Vinod Khosla cited last year. Mazama plans to start generating electricity next year and aims to complete development of the first site by 2030, producing 200 megawatts.
Enhanced geothermal startups are emerging as a dark horse in the battle to power AI data centers. While tech companies have largely backed natural gas for compute power, geothermal startups have been quietly advancing. Tapping just 1% of super-hot rock worldwide could generate more than 63 terawatts of electricity, according to the University of Twente and the Clean Air Task Force.
The round was led by Centaurus Capital and Doerr Capital, with participation from ConocoPhillips and Shell Ventures. Existing investors Khosla Ventures and Gates Frontier returned, alongside new investors SiteGround Capital, H. Barton Asset Management, and the Jeffrey and Marieke Rothschild Foundation.
