Sage Geosystems has kept a 3-megawatt enhanced geothermal plant grid-connected near San Antonio for more than 120 days, making the Houston startup only the third operator in the U.S. to bring the technology to commercial power production.

The plant, sited on land near a coal-fired station in Christine, Texas, under a 2024 agreement with San Miguel Electric Cooperative, has been running since April. Sage built its own substation at the site and sells power intermittently into the Texas grid. CEO Cindy Taff said the facility has performed reliably and as predicted across the operating period.

Only two other enhanced geothermal systems have ever connected to the U.S. grid. Ormat Technologies completed a 1.7-MW demonstration at its Desert Peak facility in western Nevada in 2013, then returned its focus to conventional geothermal; Ormat has confirmed that the demonstration no longer generates power. A decade later, Fervo Energy began operating a 3.5-MW plant in northern Nevada with Google and is now building a 500-MW facility in Utah, set to come partially online in October.

The Texas results will "directly inform and de-risk" Sage's next step, Taff said: a collaboration with Ormat in Nevada that is itself the precursor to a 150-MW development contract with Meta. Sage expects to begin drilling its first well at one of Ormat's conventional Nevada plants later this year, delivering hot water to the existing facility so Sage can prove its technology without financing a grid interconnection or building a power plant of its own. The company has not specified the system's capacity, but targets first electricity in 2027 and full-scale production in 2028.

The water number that matters

Enhanced geothermal systems drill into hot rock, fracture it, and use the heat to generate power — a departure from conventional plants that depend on what Taff called "very unicorn geology": the rare sites where water, heat and permeable rock coincide naturally.

Sage's variant creates a network of fractures into which it pumps and stores large volumes of water. As hot water presses against the surrounding rock, mechanical pressure builds and releases when operators open a valve at the surface. Other enhanced projects, by contrast, flow water through fractures between two wells without maintaining pressure.

Both designs share a vulnerability: water migrating into surrounding formations as it moves through the fracture network. The more water a project loses, the less efficiently it produces energy. Sage recorded water losses below 10% of cycled volumes on multiple occasions — a figure Taff said carries weight beyond the company's own pipeline.

"The net power output that you can produce from these technologies is going to go up," she said, arguing that curbing water loss is what will let enhanced systems scale commercially at competitive cost.

The pilot gives Sage the operating data to underwrite its downstream commitments. The plant allows the company to "actually model and predict how the [reservoir] behavior is going to be going forward," Taff said. "And that sets us up very nicely for scaling and building commercial facilities with our approach."

From storage play to firm power

Sage originally developed the Texas site with a different product in mind: a long-duration energy storage system leveraging similar geothermal techniques. Texas has since built one of the largest grid-battery fleets in the world, weakening the case for a novel storage technology. Sage has pivoted to supplying around-the-clock clean electricity, a demand segment where data-center growth is pulling capacity contracts toward firm low-carbon generation.

On paper, the company has lined up roughly a gigawatt of projects. The first and largest named commitment is the 150-MW Meta development east of the Rocky Mountains, which begins once the Ormat joint system reaches full production in 2028.

The milestones that decide what happens next are concrete: first spud at the Ormat Nevada site later this year, first electricity from that system in 2027, and full-scale output in 2028 — the gate that opens the Meta build-out.