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Houston clean energy storage facility goes online to power ERCOT grid

Jupiter Power's Callisto I is up and running. Photo courtesy of jupiterpower.io

A new battery energy storage facility in Houston is officially up and running to power the ERCOT grid with a supply of reliable, zero emissions power.

Jupiter Power announced the commercial operations launch of its 400-megawatt-hour battery facility, Callisto I, in central Houston on the site of the former HL&P H.O. Clarke fossil fuel power plant.

"Jupiter couldn't be prouder about bringing the Callisto I project online," Andy Bowman, CEO of Jupiter Power, says in a news release. "This project responds to lawmakers' calls to increase affordable and dispatchable new generation in an area where people need more power. Callisto I is the first energy storage project at this scale in the City of Houston and will help meet Houston's growing power needs while also increasing resiliency from extreme weather events."

The new project is Jupiter Power's ninth project to deliver energy storage to ERCOT — bringing its total ERCOT fleet to 1,375-megawatt-hour capacity — but its the first in the Houston area. The company is currently developing over 11,000 megawatts of projects across the country. Founded in 2017, Jupiter Power is headquartered in Austin and has offices in Houston and Chicago.

"The announcement of Jupiter Power's Callisto I Energy Storage project is significant and exciting for the region, as it's the first large-scale transmission-connected energy storage project in the City of Houston," Jane Stricker, senior vice president at the Greater Houston Partnership and executive director at the Houston Energy Transition Initiative, adds. "This critical project will help address peak power demand and is another great example of our region's leadership in scaling and deploying impactful solutions for an all the above energy future."

Among the company's financial backers is Houston-based EnCap Energy Transition, which invested in Jupiter Power via its Fund II.

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A View From HETI

Fervo Energy claimed a top 10 spot on Time magazine and Statista’s new list of America’s Top GreenTech Companies of 2025. Photo via Getty Images.

The accolades keep rolling in for Houston-based Fervo Energy, a producer of geothermal power.

Fervo lands at No. 6 on Time magazine and Statista’s new list of America’s Top GreenTech Companies of 2025. The ranking recognizes sustainability-focused companies based on factors such as impact, financial strength, and innovation.

Time notes that Fervo broke ground in 2023 in Utah on what the company claims will be the world’s largest geothermal plant. The plant is scheduled to start supplying carbon-free electricity to the grid next year and to reach its 400-megawatt capacity in three years.

“Technologies like this only make a difference if we deploy them at large-scale in a way that can reduce carbon emissions and increase the reliability of the grid,” Fervo CEO Tim Latimer told Time in 2023.

The startup was named North American Company of the Year by research and consulting firm Cleantech Group for 2025. Fervo topped the Global Cleantech 100, Cleantech Group’s annual list of the world’s most innovative and promising cleantech companies.

Last year, Fervo also made Time’s list of the 200 Best Inventions of 2024. Fervo was recognized in the green energy category for its FervoFlex geothermal power system.

Founded in 2017, Fervo is now a unicorn, meaning its valuation as a private company exceeds $1 billion. The startup’s valuation is estimated at $1.4 billion. According to PitchBook data, the company raised $634 million in the fourth quarter of 2024.

In all, eight Houston-area companies appear among the top 250 greentech companies ranked by Time and Statista. Other than Fervo, they are:

  • No. 43 Lancium Technologies, an energy storage and distribution company
  • No. 50 Solugen, a producer of sustainable chemicals.
  • No. 56 Quaise Energy, which specializes in terawatt-scale geothermal power.
  • No. 129 Plus Power, a developer, owner and operator of battery storage projects.
  • No. 218 Dream Harvest, which promotes sustainable vertical farming.
  • No. 225 Cemvita, which uses synthetic biology to convert carbon emissions into bio-based chemicals.
  • No. 226 Syzygy Plasmonics, which decarbonizes chemical production.
Vermont-based BETA Technologies claimed the No. 1 spot. The company manufactures electric aircraft.

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