major milestone

Houston geothermal startup selects Texas location for first energy storage facility

Houston startup Sage Geosystems has tapped a utility provider for an energy storage facility in the San Antonio metro area. Photo via sagegeosystems.com

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.

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A View From HETI

Two Houston startups have landed on the 2026 Cleantech 50 to Watch list. Photo via Getty Images

Two Rice University spinouts, Coflux Purification and DexMat, appear on a new list of the world’s 50 cleantech companies to watch.

Cleantech Group’s 2026 Cleantech 50 to Watch list recognizes early-stage companies “creating groundbreaking solutions to address some of the world’s most pressing environmental and sustainability challenges.”

Cleantech Group, a market research, consulting, and events company, selects the 50 honorees based on insights from analysts and early-stage innovators, along with public nominations.

Destroying “forever chemicals”

Coflux, founded in 2024, offers an onsite treatment system that captures and destroys manufactured “forever chemicals”—per- and polyfluoroalkyl substances—in water and wastewater. It’s a member of Greentown Houston.

Alec Ajnsztajn, CEO; Jeremy Daum, chief technology officer; and Dana Vazquez, chief commercial officer, co-founded Coflux. Ajnsztajn and Daum earned doctoral degrees from Rice, and Vazquez earned an MBA from the university.

Coflux spun out of Rice labs directed by professors Rafael Verduzco and Pulickel Ajayan.

Last year, Coflux received a $175,000 grant from the U.S. Food and Drug Administration’s National Institute of Food and Agriculture. The startup has also raised more than $500,000 in non-dilutive funding, including $80,000 awarded in 2024 by Rice’s One Small Step Grant program.

Promoting an alternative to copper

DexMat, founded in 2015, produces carbon nanotube products such as fibers, yarns, cables, and fabric. The company’s products address demand for materials that can reduce carbon emissions, according to CB Insights.

Its main product, Galvorn, is a copper alternative made of carbon nanotube fibers. CB Insights says Galvorn is engineered to be lighter and stronger than traditional conductive materials like carbon and steel. It’s used in industries such as energy, aerospace, defense, automotive, consumer electronics, and health care.

DexMat emerged from Matteo Pasquali’s Carbon Lab at Rice. Pasquali, co-founder of DexMat, co-invented the company’s technology with the late Nobel Prize-winning chemist Rick Smalley. Smalley was a professor of chemistry, physics, and astronomy at Rice.

Pasquali is a professor of chemical and biomolecular engineering, chemistry, materials science, and nanoengineering at Rice. He co-founded DexMat with Rice graduate Dmitri Tsentalovich, the company’s director of product innovation.

Earlier this year, DexMat raised $5 million in seed funding from Non Sibi Ventures, Governance Partners, Tailwind Futures, BetterWay, Capital Factory, and other investors. The company also secured $3 million in non-dilutive funding.

In 2023, DexMat raised $3 million in a pre-seed round led by Shell Ventures.

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