Khosla-backed Mazama Energy just raised $135M to drill deeper into super-hot-rock geothermal

Mazama Energy said it raised $135 million in an oversubscribed Series B to fund development of horizontal wells that reach super-hot rock. The company is targeting temperatures near 750°F (400°C) at high pressure, where water can enter a supercritical state and carry substantially more energy than conventional steam. Mazama says wells accessing that regime can produce roughly 15 megawatts each and yield up to ten times the power of traditional geothermal wells.

The startup plans to begin generating electricity from its first Oregon site sometime next year and has revised its estimate for that site’s potential to about 10 gigawatts of resource capacity, up from a prior 5-gigawatt estimate reported last year. Mazama has already secured land for a second development and intends to complete development of the first site by 2030, at which point it expects the project to produce about 200 megawatts of electricity.

Mazama’s drilling program aims to reach approximately 15,000 feet beneath the surface; the company reported drilling past 10,000 feet in 15 days during initial operations. At those depths and temperatures, fluid becomes supercritical, a physical state Mazama says enables much higher energy transport and therefore higher power output per well. Independent studies cited in reporting note the larger global potential of super-hot rock: tapping just 1% of such resources could yield more than 63 terawatts of electricity.

The new financing round was led by Centaurus Capital and Doerr Capital, with participation from energy and venture investors including ConocoPhillips, Shell Ventures, returning backers Khosla Ventures and Gates Frontier, and new entrants such as SiteGround Capital, H. Barton Asset Management, and the Jeffrey and Marieke Rothschild Foundation. Mazama was originally incubated at Khosla Ventures.