Houston-based geothermal energy startup Sage Geosystems has teamed up with a utility provider for an energy storage facility in the San Antonio metro area.

The three-megawatt EarthStore facility will be on land controlled by the San Miguel Electric Cooperative, which produces electricity for customers in 47 South Texas counties. The facility will be located in the town of Christine, near the cooperative’s coal-fired power plant.

Sage says its energy storage system will be paired with solar energy to supply power for the grid operated by the Electric Reliability Council of Texas (ERCOT). The facility is set to open later this year.

“Once operational, our EarthStore facility in Christine will be the first geothermal energy storage system to store potential energy deep in the earth and supply electrons to a power grid,” Cindy Taff, CEO of Sage Geosystems, says in a news release.

The facility is being designed to store geothermal energy during six- to 10-hour periods.

“Long-duration energy storage is crucial for the ERCOT utility grid, especially with the increasing integration of intermittent wind and solar power generation,” says Craig Courter, CEO of the San Miguel Electric Cooperative.