Mazama Energy, a geothermal startup backed by Khosla Ventures, recently closed an oversubscribed Series B funding round, raising $135 million. This new capital will support the company's efforts to develop horizontal wells that tap into super-hot rock formations deep underground, with each well expected to generate up to 15 megawatts of continuous electricity. Mazama's initial site in Oregon, which they plan to start powering next year, now has an estimated capacity to produce 10 gigawatts — doubling the previous estimate from 2025.

The company focuses on enhanced geothermal systems that access rock at depths around 15,000 feet, where temperatures reach approximately 750 degrees Fahrenheit. At these super-hot conditions and high pressure, water enters a supercritical phase, enabling it to store and transfer much more energy compared to traditional steam-based geothermal methods. This breakthrough is projected to allow each well to deliver about ten times the power of conventional geothermal wells, positioning Mazama as a leader in next-generation geothermal technology.

Mazama aims to complete full development of its Oregon site by 2030, at which point it expects to produce 200 megawatts of electricity. The startup has also procured land for a second project, signaling plans for expansion. The broader potential of their technology is significant, as tapping just 1% of the world's super-hot rock could theoretically generate over 63 terawatts of electricity, according to research from the University of Twente and the Clean Air Task Force.

The recent funding round was led by Centaurus Capital and Doerr Capital, and included investments from energy giants like ConocoPhillips and Shell Ventures. Existing backers such as Khosla Ventures and Gates Frontier also participated, joined by new investors including SiteGround Capital and the Rothschild Foundation. Mazama’s rapid progress is garnering attention as enhanced geothermal emerges as a promising clean energy source for powering high-demand applications, including AI data centers that require 24/7 reliable electricity.