Mazama raises $140M Series B to scale the hottest geothermal system ever built
What's the deal? Mazama Energy has raised US$87.4M Series B to accelerate commercial development of superhot rock geothermal power. The oversubscribed round was co-led by Centaurus CapitalDealroom has a profile for this one. Try Dealroom →, founded by John Arnold, and Doerr Capital, bringing total new capital to $140 million.
Who's backing it? ConocoPhillipsDealroom has a profile for this one. Try Dealroom → and Shell VenturesDealroom has a profile for this one. Try Dealroom → joined the round, alongside repeat investors Khosla Ventures and Gates FrontierDealroom has a profile for this one. Try Dealroom →. SiteGround CapitalDealroom has a profile for this one. Try Dealroom →, H. Barton Asset ManagementDealroom has a profile for this one. Try Dealroom →, and the Jeffrey and Marieke Rothschild Foundation also participated.
What's the endgame? Mazama holds the record for the hottest engineered geothermal system ever built, reaching 629°F at Newberry, Oregon, in 2025. It is now drilling toward 750°F, a temperature it says delivers up to 10 times the power of a conventional well by tapping supercritical water.
The efficiency gains are the pitch: Mazama says its approach uses 75% less water and 80% fewer wells than conventional geothermal, shrinking the surface footprint and easing permitting.
What the money funds: The capital supports Project Ceres, backed by the US Department of Energy, which aims to advance horizontal well development toward 15 MWe per well and demonstrate power generation in 2027. Mazama is targeting certification of more than 10 GWe of resource potential at Newberry alone.
Why now? Utilities are struggling to add round-the-clock power faster than new transmission and 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," the company said.
The signal: The round sits in the top 5% of all Series B hardware rounds in the US by size, a sign of how much investor appetite has grown for firm, carbon-free power as electricity demand climbs. With oil majors and climate funds writing the same cheque, geothermal is drawing capital once reserved for solar and batteries.
Read more: Business Insider
Image credit: Mazama Energy
