This will be the first geothermal energy storage system on the Texas grid

Sage Geosystems will launch EarthStore this year, which uses geothermal energy storage to produce clean electricity on demand. The Houston-based geothermal baseload and energy storage company has entered into a land use agreement with San Miguel Electric Cooperative for a 3-megawatt (MW) geopressured geothermal system energy storage facility. The EarthStore system will be in Christine, Texas, south of San Antonio, near the SMECI lignite coal power plant. Sage will operate as a merchant, buying and selling electricity to the ERCOT grid. The project is expected to come online later in 2024. Cindy Taff, CEO of Sage Geosystems, said, “Geothermal energy storage is a viable solution for long-duration storage and an alternative for short-duration lithium-ion batteries. Electric utilities and co-ops like [San Miguel Electric Cooperative] will be able to use our technology to complement wind and solar, and stabilize the grid.” Sage’s proprietary technology will be used in Christine to store energy, targeting 6-to-10-hour storage durations and delivering a round-trip efficiency of 70-75%. In addition, water losses are targeted to be less than 2%. At scale, this energy storage system will be paired with renewable energy to provide baseload and dispatchable power to the electric grid. When combined with solar, Sage’s EarthStore facility enables 24/7 electricity generation at a blended levelized cost of energy well under $0.10/kWh. Craig Courter, CEO of San Miguel Electric Cooperative, said, “Long-duration energy storage is crucial for the ERCOT utility grid, especially with the increasing integration of intermittent wind and solar power generation. We are excited to be part of this innovative project that showcases the potential of geothermal energy storage.” Sage will apply for two drilling permits in Texas. The first permit is in Atascosa County for the EarthStore facility in Christine, and the second permit is in Starr County, adjacent to the company’s existing test well.