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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Houston Energy and Climate Startup Week announces 2025 dates, key events

comeback tour

Six local organizations focused on the energy transition have teamed up to bring back Houston Energy and Climate Startup Week.

The second annual event will take place Sept. 15-19, according to an announcement. The Ion District will host many of the week's events.

Houston Energy and Climate Startup Week was founded in 2024 by Rice Alliance for Technology and Entrepreneurship, Halliburton Labs, Greentown Labs, Houston Energy Transition Initiative (HETI), Digital Wildcatters and Activate.

“Houston Energy and Climate Startup Week was created to answer a fundamental question: Can we achieve more by working together than we can alone?” Jane Stricker, senior vice president at the Greater Houston Partnership and executive director of HETI, said in the release.

So far, events for the 2025 Houston Energy and Climate Startup Week include an introduction to climatetech accelerator Activate's latest cohort, the Rice Alliance Energy Tech Venture Forum, a showcase from Greentown Labs' ACCEL cohort, and Halliburton Labs Pitch Day.

Houston organizations New Climate Ventures and Digital Wildcatters, along with Global Corporate Venturing, are slated to offer programming again in 2025. And new partners, Avatar Innovations and Decarbonization Partners, are slated to introduce events. Find a full schedule here.

Other organizations can begin entering calendar submissions starting in May, according to the release.

Last year, Houston Energy and Climate Startup Week welcomed more than 2,000 attendees, investors and industry leaders to more than 30 events. It featured more than 100 speakers and showcased more than 125 startups.

"In 2024, we set out to build something with lasting impact—rooted in the ingenuity of Houston’s technologists and founders. Thanks to a collaborative effort across industry, academia, and startups, we’ve only just begun to showcase Houston’s strengths and invite others to be part of this movement," Stricker added in the release. "We can’t wait to see the city rise to the occasion again in 2025.”

Dow aims to power Texas manufacturing complex with next-gen nuclear reactors

Clean Energy

Dow, a major producer of chemicals and plastics, wants to use next-generation nuclear reactors for clean power and steam at a Texas manufacturing complex instead of natural gas.

Dow's subsidiary, Long Mott Energy, applied Monday to the U.S. Nuclear Regulatory Commission for a construction permit. It said the project with X-energy, an advanced nuclear reactor and fuel company, would nearly eliminate the emissions associated with power and steam generation at its plant in Seadrift, Texas, avoiding roughly 500,000 metric tons of planet-warming greenhouse gas emissions annually.

If built and operated as planned, it would be the first U.S. commercial advanced nuclear power plant for an industrial site, according to the NRC.

For many, nuclear power is emerging as an answer to meet a soaring demand for electricity nationwide, driven by the expansion of data centers and artificial intelligence, manufacturing and electrification, and to stave off the worst effects of a warming planet. However, there are safety and security concerns, the Union of Concerned Scientists cautions. The question of how to store hazardous nuclear waste in the U.S. is unresolved, too.

Dow wants four of X-energy's advanced small modular reactors, the Xe-100. Combined, those could supply up to 320 megawatts of electricity or 800 megawatts of thermal power. X-energy CEO J. Clay Sell said the project would demonstrate how new nuclear technology can meet the massive growth in electricity demand.

The Seadrift manufacturing complex, at about 4,700 acres, has eight production plants owned by Dow and one owned by Braskem. There, Dow makes plastics for a variety of uses including food and beverage packaging and wire and cable insulation, as well as glycols for antifreeze, polyester fabrics and bottles, and oxide derivatives for health and beauty products.

Edward Stones, the business vice president of energy and climate at Dow, said submitting the permit application is an important next step in expanding access to safe, clean, reliable, cost-competitive nuclear energy in the United States. The project is supported by the Department of Energy’s Advanced Reactor Demonstration Program.

The NRC expects the review to take three years or less. If a permit is issued, construction could begin at the end of this decade, so the reactors would be ready early in the 2030s, as the natural gas-fired equipment is retired.

A total of four applicants have asked the NRC for construction permits for advanced nuclear reactors. The NRC issued a permit to Abilene Christian University for a research reactor and to Kairos Power for one reactor and two reactor test versions of that company's design. It's reviewing an application by Bill Gates and his energy company, TerraPower, to build an advanced reactor in Wyoming.

X-energy is also collaborating with Amazon to bring more than 5 gigawatts of new nuclear power projects online across the United States by 2039, beginning in Washington state. Amazon and other tech giants have committed to using renewable energy to meet the surging demand from data centers and artificial intelligence and address climate change.

Houston geothermal company closes $13M in investments to fuel growth

fresh funding

XGS Energy, a California-headquartered geothermal power company with a major presence in Houston, has closed $13 million in new financing that included new investors Aligned Climate Capital, ClearSky, ClimateIC and WovenEarth Ventures, in addition to inside investors.

The company plans to “aggressively expand” its team in Houston this year, according to a news release.

“We are facing global energy supply challenges of unprecedented scale and urgency,” Kevin Kimsa, Managing Partner at ClimateIC, said in the release. “The XGS team is uniquely primed to meet the moment, bringing together innovative technology and leading engineering talent with the deep experience in infrastructure development and financing critical to deploying large-scale energy systems at speed.”

As part of the financing deal, Mano Nazar, ClearSky Senior Advisor and the former Chief Nuclear Officer of NextEra Energy, will join the XGS Energy Board of Directors.

“XGS’s advanced geothermal technology is uniquely positioned to deliver abundant energy to the grid faster than any other baseload energy technology at a time of unprecedented demand for energy resources,” Nazar said in a news release. “We are excited to partner with XGS to deliver on their mission of sustainable, reliable, and scalable geothermal energy.”

XGS is known for its next-gen closed-loop geothermal well architecture. The company saw massive growth in the Houston market last year and recently completed a 100-meter field demonstration in central Texas. The new funding supports the XGS’s multi-gigawatt project pipeline.

The recent financing also builds on an oversubscribed Series A round led by Constellation Technology Ventures, VoLo Earth Ventures, and Valo Ventures that closed last year.