Mazama Energy raises $135M for superhot geothermal wells at Newberry

Mazama Energy announced $135 million in new capital on September 17, 2026, including an oversubscribed Series B led by Centaurus Capital and Doerr Capital, "to accelerate superhot rock geothermal commercial development." Its site is Newberry, Oregon, where the company says it built the hottest engineered geothermal system (EGS) yet, at 629°F (331°C), in 2025. The release says ConocoPhillips and Shell Ventures joined the round, Khosla Ventures and Gates Frontier invested again, and SiteGround Capital, H. Barton Asset Management and the Jeffrey and Marieke Rothschild Foundation also took part; its subheadline says the capital enables Mazama "to push beyond 750°F."

The release calls the 2025 system the record for the hottest EGS ever built, "proving reservoir creation, connectivity and heat recovery." Its second well, Project Athena, is drilling about a mile deeper toward 750°F (400°C), and the release says Athena reached "that same 10,350-foot depth" in 15 days, about 80% faster than the 2025 well. The company's own documents disagree on that depth. Mazama's September 1, 2026 release says Athena reached 10,350 feet in 15 drilling days, "the target depth of the well Mazama drilled in 2025"; its October 28, 2025 release described "a new, 10,200-foot deviated producer well," a paper by its engineers gives that well's total measured depth as 3,109 m (10,200 ft), and the company's website, republished the same day as the September 17 release, still says "We drilled 10,200 ft." The two 2026 wire releases carry 10,350 feet; the October 2025 release, the February 2026 paper and the current website carry 10,200. The September 1 release puts Athena's planned total depth at about 15,500 feet.

The case for 750°F is the company's: the September 17 release says reaching it "delivers up to 10 times the power of a conventional 390°F (200°C) well," owing to supercritical water's energy density, and that this lets Mazama deliver projects "using 75% less water and drilling 80% fewer wells than conventional geothermal developments," two figures the company's website states as "up to." Those are targets for a well the company has not finished drilling.

What the money funds

The release says the financing funds Project Ceres, "supported by the U.S. Department of Energy," which will advance horizontal well development in superhot rock toward 15 MWe of capacity per well and demonstrate power generation in 2027. The September 1 release said Ceres would drill "the first ever commercial-scale superhot rock horizontal wells" in Q4 2026. The October 2025 release had a tighter schedule: Mazama would advance to horizontal wells "beginning with a 15 MW pilot in 2026 and then scaling to a 200 MW development project at Newberry." Read together, the drilling has held to 2026 and the power demonstration has moved to 2027; the September 17 release does not address the change. The basis has shifted too: the 2025 release described a 15 MW pilot, the company's website describes Ceres as two horizontal wells in rock up to 710°F "targeting 15 megawatts of initial power generation," and the September 17 release states 15 MWe per well.

Ceres has a federal decision on its operations plan. The Bureau of Land Management's Deschutes Field Office "issued a decision record for a categorical exclusion to authorize Mazama Energy's Geothermal Operations Plan," the BLM's Prineville District announced on July 24, 2026, naming the record "Mazama Energy - Project Ceres Geothermal Operations Plan." The announcement names no wells, dates or permits and does not describe the plan's contents; the company's February 2026 paper, cited below, places surface oversight of the site with the U.S. Forest Service.

The DOE support is a Geothermal Technologies Office award under its EGS Pilot Demonstrations program, whose project list describes Mazama's entry as a demonstration of super-hot EGS on the western flank of Newberry Volcano. A GTO article dated January 14, 2025 says the office is funding Mazama to apply its MUSE technology at Newberry and that the project follows an earlier GTO-funded EGS project at the same volcano. Neither DOE page states the award's size; Central Oregon broadcaster KTVZ reported on December 20, 2024 that Mazama said it had received a $20 million DOE grant, and carried the company's boilerplate that its capabilities derive from its founders AltaRock Energy and Blade Energy Partners. AltaRock's Newberry demonstration is the federal-land precedent The Duck Curve noted when Hexagon Energy leased approximately 145,000 acres of Weyerhaeuser geothermal rights on September 10, 2026.

The measured baseline comes from the company's own engineers. A paper Mazama staff presented at the Stanford Geothermal Workshop in February 2026 reports that the 2025 work reworked the existing well 55-29 as the injector, a well its abstract puts at 3,008 m deep with a 331°C bottomhole temperature and its well section at an original total depth of 3,066 m, with access restored to near 3,045 m, and drilled 55A-29 as the producer to 3,109 m. A flow test that ran as a step-rate test for its first four weeks delivered up to 4.5 MW thermal, "for an equivalent power of approximately 0.7 MWe." The paper places the site on federal land administered by the Bureau of Land Management, "with surface oversight by the U.S. Forest Service," immediately adjacent to Newberry National Volcanic Monument, and says stimulating the two wells induced 150 microseismic events between magnitude -2.0 and -0.6, with no reservoir-linked seismicity detected since August 2025. The distance from 0.7 MWe measured at a slightly deviated well pair to the 15 MWe per horizontal well the release targets is what Ceres is meant to close.

The Duck Curve has followed a run of engineered geothermal projects: Fervo Energy signed a 396 MW power purchase agreement with Google on August 26, 2026 for its Cape Station project in Utah, where Fervo's quarterly filing says 500 MW is under construction with first power expected by late 2026, and Sage Geosystems put a 3 MW Texas plant in service in August 2026. Mazama's three releases and its website name no buyer. The website describes a 200 MW plant at Newberry with first power targeted for 2029 and full output in 2030, and the September 1 release quotes CEO Sriram Vasantharajan expecting the first commercial project at Newberry to achieve $4,500 to $4,950 per kilowatt in initial development cost.

Outlook

If Athena reaches its planned 15,500 feet and the 750°F the releases target, the next dated markers are the Q4 2026 start of Ceres's horizontal wells and the 2027 power demonstration; the pilot date in the October 2025 release has already moved once, so 2027 reads as a target rather than a schedule. Fervo's Cape Station, with first power expected by late 2026 per its filing, is due to produce before Ceres if that schedule holds, leaving Newberry's 2027 test as the first field check on the per-well multiple Mazama claims. The more than 10 GWe of resource potential the release says Mazama is targeting for independent certification at Newberry is a certification the company has yet to obtain.

Hero: the Newberry demonstration site on June 20, 2014, during AltaRock Energy's earlier EGS project, in a Bureau of Land Management photo.