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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

Researchers Rahul Pandey, senior scientist with SRI and principal investigator (left), and Praveen Bollini, a University of Houston chemical engineering faculty, are key contributors to the microreactor project. Photo via uh.edu

A University of Houston-associated project was selected to receive $3.6 million from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy that aims to transform sustainable fuel production.

Nonprofit research institute SRI is leading the project “Printed Microreactor for Renewable Energy Enabled Fuel Production” or PRIME-Fuel, which will try to develop a modular microreactor technology that converts carbon dioxide into methanol using renewable energy sources with UH contributing research.

“Renewables-to-liquids fuel production has the potential to boost the utility of renewable energy all while helping to lay the groundwork for the Biden-Harris Administration’s goals of creating a clean energy economy,” U.S. Secretary of Energy Jennifer M. Granholm says in an ARPA-E news release.

The project is part of ARPA-E’s $41 million Grid-free Renewable Energy Enabling New Ways to Economical Liquids and Long-term Storage program (or GREENWELLS, for short) that also includes 14 projects to develop technologies that use renewable energy sources to produce sustainable liquid fuels and chemicals, which can be transported and stored similarly to gasoline or oil, according to a news release.

Vemuri Balakotaiah and Praveen Bollini, faculty members of the William A. Brookshire Department of Chemical and Biomolecular Engineering, are co-investigators on the project. Rahul Pandey, is a UH alum, and the senior scientist with SRI and principal investigator on the project.

Teams working on the project will develop systems that use electricity, carbon dioxide and water at renewable energy sites to produce renewable liquid renewable fuels that offer a clean alternative for sectors like transportation. Using cheaper electricity from sources like wind and solar can lower production costs, and create affordable and cleaner long-term energy storage solutions.

“As a proud UH graduate, I have always been aware of the strength of the chemical and biomolecular engineering program at UH and kept myself updated on its cutting-edge research,” Pandey says in a news release. “This project had very specific requirements, including expertise in modeling transients in microreactors and the development of high-performance catalysts. The department excelled in both areas. When I reached out to Dr. Bollini and Dr. Bala, they were eager to collaborate, and everything naturally progressed from there.”

The PRIME-Fuel project will use cutting-edge mathematical modeling and SRI’s proprietary Co-Extrusion printing technology to design and manufacture the microreactor with the ability to continue producing methanol even when the renewable energy supply dips as low as 5 percent capacity. Researchers will develop a microreactor prototype capable of producing 30 MJe/day of methanol while meeting energy efficiency and process yield targets over a three-year span. When scaled up to a 100 megawatts electricity capacity plant, it can be capable of producing 225 tons of methanol per day at a lower cost. The researchers predict five years as a “reasonable” timeline of when this can hit the market.

“What we are building here is a prototype or proof of concept for a platform technology, which has diverse applications in the entire energy and chemicals industry,” Pandey continues. “Right now, we are aiming to produce methanol, but this technology can actually be applied to a much broader set of energy carriers and chemicals.”

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