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Houston-based geothermal energy startup releases promising results of Texas pilot

Houston startup Sage Geosystems released the results of its pilot at a Shell-drilled oil well in the Rio Grande Valley’s Starr County. Photo via sagegeosystems.com

As it seeks an additional $30 million in series A funding, Houston startup Sage Geosystems has released promising results from a test of its technology for underground storage of geothermal energy.

Sage says the pilot project, conducted at a Shell-drilled oil well in the Rio Grande Valley’s Starr County, showed the company’s long-term energy storage can compete on a cost basis with lithium-ion battery storage, hydropower storage, and natural gas-powered peaker plants. Peaker plants supply power during periods of peak energy demand.

Furthermore, Sage’s geothermal technology will provide more power capacity at half the cost of other advanced geothermal systems, the company says.

Sage’s storage system retrofits oil and gas wells with the company’s geothermal technology. But the company says its technology “can be deployed virtually anywhere.”

The system relies on mechanical storage instead of battery storage. In mechanical storage, heat, water, or air works in tandem with compressors, turbines, and other machinery. By contrast, battery storage depends on chemistry to get the job done.

“We have cracked the code to provide the perfect complement to renewable energy. … The opportunities for our energy storage to provide power are significant — from remote mining operations to data centers to solving energy poverty in remote locations,” former Shell executive Cindy Taff, CEO of Sage, says in a September 12 news release.

Sage says its storage capacity can be connected to existing power grids, or it can develop microgrids that harness stored energy.

An August 2023 article in The New York Times explained that Sage “is pursuing fracked wells that act as batteries. When there’s surplus electricity on the grid, water gets pumped into the well. In times of need, pressure and heat in the fractures pushes water back up, delivering energy.”

The pilot project, a joint venture between Sage and the Bureau of Economic Ecology at the University of Texas at Austin, was performed as part of a feasibility study financed by the Air Force. Now that the test results are in, Sage plans to build a prototype geothermal project at the Air Force’s Ellington Field Joint Reserve Base in Houston.

Sage says another feasibility study is underway in the Middle East in partnership with an unnamed oil and gas company.

Founded in 2020, Sage plans to raise another $30 million to accompany its previous series A funding.

The Virya climate fund and Houston-based drilling contractor Nabors Industries helped finance the pilot project in Starr County.

Last year, Sage announced it received an undisclosed amount of equity from Houston-based Ignis H2 Energy, a geothermal exploration and development company, and Dutch energy company Geolog International. Also last year, Sage said Nabors and Virya had teamed up for a $12 million investment in the startup.

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A View From HETI

Houston-based Mati Carbon won the global XPRIZE Carbon Removal competition, funded by The Musk Foundation. Photo via LinkedIn.

Houston-based Mati Carbon has won the $50 million grand prize in the XPRIZE Carbon Removal competition, backed by Elon Musk’s charitable organization, The Musk Foundation.

Mati was selected in 2024 as one of 20 global finalists. The company removes carbon through its Enhanced Rock Weathering (ERW) program that works with agricultural farms in Africa and India.

The 3-year-old startup accelerates the natural process of rock weathering (ERW) by applying pulverized basalt to croplands of partnered smallholder farmers, free of charge. Mati says the farmers it partners with are some of the most vulnerable to the impacts of climate change.

“Winning this XPRIZE competition is an incredible honor and a definitive validation of our research and development, and building out the infrastructure needed to impact millions of farmers while delivering verifiable carbon dioxide removal at a gigaton scale,” Mati Carbon Founder and CEO Shantanu Agarwal, said in a news release. “I couldn’t be prouder, not just of the Mati team, but of our collaborators, research partners and the thousands of smallholder farmers who let us be part of their lives. This XPRIZE recognition will allow us to collaborate with local partners to accelerate the use of enhanced rock weathering across the Global South.”

Mati reports that it plans to use the award to “scale its efforts working with smallholder farmers worldwide.” Apart from the XPRIZE funding, Mati plans to grow its model through the sale of CDR credits. According to the company, it counts Shopify, Stripe, and H&M among its early carbon credit buyers.

“Mati Carbon’s deployments bolster farmers’ livelihoods through improved soil health, reduced agricultural inputs, and increased income at zero cost to them. Mati Carbon’s team has developed a scientifically rigorous approach to monitoring and verification, and excelled across each of XPRIZE’s prize evaluation criteria – operational, sustainability, and cost metrics – giving the XPRIZE judges the highest confidence in Mati Carbon’s solution’s long-term scalability,” the XPRIZE judges wrote.

Houston-based Vaulted Deep took home the second-runner-up prize in the competition and $8 million for its organic waste storage process. The company provides permanent carbon storage by injecting nonhazardous organic waste deep underground. It spun off with $8 million in seed funding from Advantek Waste Management Services in 2023.

"Our approach is grounded in geomechanical injection techniques that have been safely deployed globally for decades by our team and predecessors," Omar Abou-Sayed, co-founder and executive chairman of Vaulted, said in a separate release. "XPRIZE recognized that this is a proven approach—already in use, delivering impact, and built on the kind of reliability the industry needs to scale responsibly."

Launched in 2021, the four-year XPRIZE Carbon Removal competition challenged global innovators to deploy scalable solutions for removing carbon dioxide from the atmosphere and oceans. More than 1,300 teams from 88 countries competed. XPRIZE finalists were required to remove at least 1,000 tonnes of CO2 over a one-year demonstration period.

French company NetZero took home the first-runner-up prize of $15 million, and London-based UNDO came in as third-runner-up with a $5 million prize.

Since the announcement of the XPRIZE Carbon Removal competition, the Musk-led Department of Government Efficiency has cut climate funding for agencies, projects and research. While the Musk Foundation sponsored the XPRIZE event, it is not affiliated with the California-based organization, according to the Associated Press.

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