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XGS Energy, an advanced-geothermal startup, says it has completed crucial testing that proves its novel technology can operate reliably at commercial scale — without losing a drop of water in the process.
The milestone, announced on Tuesday, will allow Houston-based XGS to begin financing and building its first next-generation geothermal energy project, according to the company. XGS is partnering with Meta and the utility PNM to develop 150 megawatts of around-the-clock clean electricity in New Mexico that will supply the tech giant’s data centers.
“We’re really off to the races now,” said Josh Prueher, the CEO of XGS. The startup is slated to deploy the project’s first 5 MW by around 2027 and bring the remaining megawatts online by 2029, he added.
XGS is part of a fast-growing industry that’s working to harness the world’s abundant geothermal resources to meet soaring electricity demand. Dozens of U.S. companies are developing cutting-edge technologies that promise to access Earth’s heat in drier, deeper, and hotter conditions than is technically or economically feasible for conventional geothermal plants. Another of these firms, Sage Geosystems, is also partnering with Meta to build its own 150-MW geothermal facility somewhere east of the Rocky Mountains.
Today, geothermal energy represents about 0.4% of total U.S. electricity generation, and most facilities are concentrated around geysers and hot springs in Northern California and Nevada.
The next-generation geothermal projects that are currently in development fall into one of three buckets. Enhanced geothermal systems, like the ones that Sage and Fervo Energy are building, involve fracturing rocks and pumping them full of water to create artificial reservoirs far below the earth’s surface. Superhot geothermal, which scientists are studying in Iceland, aims to tap into extreme resources like magma chambers to extract gargantuan amounts of heat.
XGS’s approach falls into the third bucket: closed-loop systems, which entail placing pipes deep underground and sealing them off so that they operate like radiators. As water circulates within the system, it collects heat from the hot rocks below and brings it to the surface, where the heat produces steam that drives electric turbines.
What sets XGS apart from its closed-loop competitors, such as Canadian startup Eavor, is the “thermally conductive” cement alternative that the company places between the hot rock and pipe system. XGS claims its proprietary material, which includes a naturally occurring mineral, can increase the total amount of heat it pulls from the subsurface by 30% to 50%, allowing the company to use simpler and cheaper well designs to access hotter rocks with existing drilling technologies.
XGS completed its first pilot project in late 2024 with a 100-meter-deep well in central Texas. Earlier this year, the startup began operating a full-scale prototype using an idled well at the Coso geothermal field in the Western Mojave Desert region of California. The well runs more than 1,000 meters deep — a standard depth for commercial geothermal wells — and reaches subsurface temperatures of around 200 degrees Celsius (392 degrees Fahrenheit).
For 3,000 hours, or 125 days, XGS continuously ran its closed-loop system while adjusting key variables, such as the rate at which liquid flows and the amount of heat extracted at the surface. The idea was to simulate how the technology performs in different operating conditions, in order to prove it can withstand various types of stress while also demonstrating the company can accurately predict the system’s performance.
The startup claims the prototype’s actual performance fell within 2% of its predictions, results that XGS later verified with independent engineers, Prueher said. Being able to accurately predict how a project will perform — and for how long — is an essential step for the company to be able to raise the many millions of dollars in debt financing it needs to build its first geothermal power plants, he added.
“This unlocks a huge commercial pipeline that has been accumulating in parallel,” Prueher said of the test results. Along with the 150 MW it’s developing with Meta, the startup has lined up over 3 gigawatts of projects “mostly in the Western United States, where water sensitivity is a huge issue, and where there’s a strong demand signal from data centers and other types of clean energy consumers to build this as quickly as we can.”
XGS has raised $55 million so far from private investors to develop its heat-harvesting technology. One of its biggest backers is VoLo Earth Ventures, which focuses on early-stage climatetech companies.
Joe Goodman, a managing partner for VoLo, said his firm identified XGS “as one of the leading geothermal solutions” about a year and a half ago after reviewing its experimental lab data, and Goodman later joined XGS’s board of directors.
By boosting the system’s overall energy output, XGS’s thermally conductive materials could be the key to making closed-loop geothermal more economically viable, he said, adding that the technology also sidesteps the concerns around water-supply constraints facing enhanced geothermal systems.
“We’re quite optimistic about what we’ve seen,” Goodman said.
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