8 Houston energy companies land on Time's top greentech list for 2025

top honor

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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Plus Power's storage facility, being built on 13 acres in Comal County, is scheduled to come online this spring. Photo courtesy of Plus Power

Houston-based developer claims $98 million tax equity investment for Texas energy storage facility

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The Woodlands-based Plus Power has collected an estimated $98 million tax equity investment for its 200-megawatt Ebony Energy Storage facility near San Antonio.

Plus Power says the investment from Solana Beach, California-based Greenprint Capital Management will help stabilize the Energy Reliability Council of Texas (ERCOT) power system “during dynamic summer demand and cold winter storms while helping to integrate more renewable energy into the grid.”

The storage facility, being built on 13 acres in Comal County, is scheduled to come online this spring.

Peter DeFazio, managing director of Greenprint, calls Plus Power “a first mover” among owner-operators of standalone battery energy storage facilities in the U.S. Plus Power owns a portfolio of large-scale lithium-ion battery systems in more than 25 states and Canada.

“As the state and the country experience increasingly extreme temperatures, we are proud that our projects can provide grid services that will help ERCOT increase reliability and meet abnormally high demand,” says Josh Goldstein, chief financial officer of Plus Power.

By this summer, Plus Power expects to be operating four storage plants in the ERCOT market with 800 megawatts of total capacity.

Plus Power announced in 2023 that it completed a $1.8 billion financing for Ebony and four other projects in Texas and Arizona. The financing included $196 million in construction and term financing for the Comal County project.

Plus Power has announced its Oahu, Hawaii, facility is up and running. Photo via pluspower.com

Houston clean energy company goes online with Hawaii facility

aloha

Houston-based Plus Power announced it has begun operating a new facility on Oahu, Hawaii.

The Kapolei Energy Storage, or KES, facility is “the most advanced grid-scale battery energy storage system in the world,” which will help transition the state's electric power from coal and oil to solar and wind, according to the company.

The KES battery project is located on 8 acres of industrial land on the southwest side of Oahu near Honolulu, and will use 158 Tesla Megapack 2 XL lithium iron phosphate batteries. It will offer the grid 185 megawatts of total power capacity and 565 megawatt-hours of electricity. This will act as an electrical "shock absorber" that will be served by combustion-powered peaker plants to respond in 250 milliseconds according to Power Plus.

"This is a landmark milestone in the transition to clean energy," Brandon Keefe, Plus Power's executive chairman, says in a news release. "It's the first time a battery has been used by a major utility to balance the grid: providing fast frequency response, synthetic inertia, and black start. This project is a postcard from the future — batteries will soon be providing these services, at scale, on the mainland."

The KES plant interconnects three of Hawaiian Electric's critical power generation facilities, which can enable KES to support the reboot of power plants in the event of a state-wide emergency.The KES batteries will help replace the grid capacity formerly provided by an AES coal power plant.

By June 2024, Plus Power aims to operate seven large-scale battery energy storage plants across Arizona and Texas. Last year, the company secured $1.8 billion in new financing for a handful of ongoing projects — most of which are in Texas.

Five of Plus Power's projects received financing from nearly a dozen financial partners. Photo courtesy of Plus Power

Houston renewable energy storage developer secures $1.8B in financing

money moves

A Houston company that develops standalone battery energy storage systems has reportedly secured $1.8 billion in new financing for a handful of ongoing projects — most of which are in Texas.

"Over the last year, Plus Power has raised an unparalleled amount of capital for standalone storage projects from a wide range of leading energy project finance banks and investors," Josh Goldstein, CFO of Plus Power, says in a news release. "This capital will support the ongoing buildout of the largest and most diverse portfolio of standalone storage projects in the U.S. The scale highlights our first-mover advantage in bringing high-quality projects to market as well as the tremendous work by our fantastic team."

The funding will be distributed to the following projects, which are expected to have a total of 1,040 megawatts of capacity, according to the release:

The 250-megawatt Sierra Estrella Energy Storage facility in Avondale, Arizona, west of Phoenix will use $707 million of the financing — $202 million of tax equity and a $505 million construction, term loan, and letter of credit facility from Bank of America. Expected to deliver by summer of next year, the 11-acre facility will be the largest to date for a standalone energy storage project, according to Plus Power.
$212.2 million of tax equity financing from Foss & Company, as well as $276 million of construction and term financing, for the 300 MW / 600 MWh Rodeo Ranch Energy Storage facility in Pecos.
$196 million of construction and term financing for the 200 MW / 400 MWh Ebony Energy Storage facility in Comal County, northeast of San Antonio.
$200 million of construction and term financing for the 200 MW / 400 MWh Anemoi Energy Storage facility in Hidalgo County, on the Mexican border northwest of Matamoros.
$196 million construction, term loan and letter of credit facility for the 90 MW / 360 MWh Superstition Energy Storage project in Gilbert, southeast of Phoenix.

The $884 million committed to three new standalone storage facilities in Texas bring Plus Power's current ERCOT portfolio to 800 MW. Deutsche Bank and First Citizens Bank were the coordinating lead arrangers, per the news release.

"Plus Power is a market leader in the battery energy storage sector and we are honored to have collaborated with them on these breakthrough financings," Jeremy Eisman, managing director and head of Infrastructure & Energy Financing at Deutsche Bank, says in a statement. "We acknowledge the important role that battery storage plays in ensuring a clean and reliable electric grid and look forward to continuing to support the Plus Power team's continued growth in this sector."

Plus Power's portfolio includes large-scale lithium-ion battery systems across 25 states and Canada. The company reports that three of the projects will be completed before next year's summer heat rolls back in.

Originally founded in San Francisco in 2018, Plus Power moved its HQ to Houston last year. The company recently signed a lease for nearly 7,000 square feet at Three Hughes Landing in The Woodlands. The company previously was based in coworking space at the Rayford Office Park in Spring.

Plus Power, which recently relocated its HQ to Houston, has moved into a larger office space. Image via cushmanwakefield.com

Energy storage startup moves into larger Houston-area space, plans to grow team

expansion plans

A Northern California-born energy storage startup has established its headquarters in The Woodlands.

Plus Power, which develops battery systems designed to store backup power for electric grids, recently signed a lease for nearly 7,000 square feet at Three Hughes Landing in The Woodlands. The company previously was based in coworking space at the Rayford Office Park in Spring.

The company, founded in 2018, shifted its headquarters from San Francisco to the Houston area last year.

“We chose The Woodlands for its beauty, and walkable access to great nearby hotels, restaurants, and healthy groceries,” says Brandon Keefe, CEO of Plus Power. “A Houston base reflects our deep focus on the Texas market, as we are investing nearly $1 billion in several projects here that will be online by the first quarter of 2024, with more in [the works] behind that.”

About 40 employees work from Plus Power’s new office in The Woodlands. Across North America, the company employs about 130 people, including several in Austin. As of July 10, the startup listed nine job openings.

Plus Power develops, owns, and operates utility-scale systems that store energy in huge lithium-ion batteries during low-demand periods. In times of peak demand, power providers can tap into this stored energy.

“Standalone energy storage is rapidly transforming the U.S. energy markets, because it is cheaper than new natural gas plants, faster to build than fossil peakers or transmission, and able to perform diverse energy services,” the company explains in its job postings.

Peakers are backup power plants that run on fossil fuels.

One of Plus Power’s storage facilities is the 100-megawatt Gambit project, which opened two years ago in Angleton. The nearly eight-acre facility supports power supplies for the Electric Reliability Council of Texas (ERCOT), which runs the power grid for 90 percent of Texas.

The company says the Angleton facility has fed backup energy to ERCOT during this year’s and last year’s heatwaves, as well as last December’s winter freeze.

The Gambit facility might ring a bell with some folks in the Houston area. In January 2022, Austin-based automaker Tesla unveiled a backup power storage facility in Angleton. Plus Power bought the project from Tesla in June 2022.

Plus Power’s development pipeline contains 10 gigawatts’ worth of energy storage projects in 28 states and Canada. That includes massive projects on tap for Hawaii and Arizona.

Last November, Plus Power announced it had secured $219 million in debt financing for construction of the 185-megawatt Kapolei project on a roughly eight-acre site in Oahu, Hawaii. The facility will be tied to Hawaiian Electric’s power grid. Mizuho Securities USA and KeyBank led the financing.

This April, Plus Power held a groundbreaking ceremony for the Sierra Estrella project in Tolleson, a Phoenix suburb. The 250-megawatt system will serve Salt River Project (SRP), a utility provider in the Phoenix area. The roughly 11-acre Tolleson facility is set to open next year, as is another Plus Power project for SRP — the 90-megawatt Superstition facility in Gilbert, another Phoenix suburb.

As its development pipeline demonstrates, Plus Power is firmly plugged into the fast-growing energy storage market.

According to the Houston-based energy research and consulting firm Wood Mackenzie and the American Clean Power Association, the U.S. energy storage market installed a record-breaking 4.8 gigawatts of capacity in 2022. This year, that number is projected to approach 75 gigawatts.

In a March 2023 news release, John Hensley, the clean power group’s vice president of research and analytics, says the U.S. market “is on a rapid growth curve and is already a key component of building a resilient grid that supports abundant clean energy.”

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Houston geothermal company raises $97M Series B

fresh funding

Houston-based geothermal energy startup Sage Geosystems has closed its Series B fundraising round and plans to use the money to launch its first commercial next-generation geothermal power generation facility.

Ormat Technologies and Carbon Direct Capital co-led the $97 million round, according to a press release from Sage. Existing investors Exa, Nabors, alfa8, Arch Meredith, Abilene Partners, Cubit Capital and Ignis H2 Energy also participated, as well as new investors SiteGround Capital and The UC Berkeley Foundation’s Climate Solutions Fund.

The new geothermal power generation facility will be located at one of Ormat Technologies' existing power plants. The Nevada-based company has geothermal power projects in the U.S. and numerous other countries around the world. The facility will use Sage’s proprietary pressure geothermal technology, which extracts geothermal heat energy from hot dry rock, an abundant geothermal resource.

“Pressure geothermal is designed to be commercial, scalable and deployable almost anywhere,” Cindy Taff, CEO of Sage Geosystems, said in the news release. “This Series B allows us to prove that at commercial scale, reflecting strong conviction from partners who understand both the urgency of energy demand and the criticality of firm power.”

Sage reports that partnering with the Ormat facility will allow it to market and scale up its pressure geothermal technology at a faster rate.

“This investment builds on the strong foundation we’ve established through our commercial agreement and reinforces Ormat’s commitment to accelerating geothermal development,” Doron Blachar, CEO of Ormat Technologies, added in the release. “Sage’s technical expertise and innovative approach are well aligned with Ormat’s strategy to move faster from concept to commercialization. We’re pleased to take this natural next step in a partnership we believe strongly in.”

In 2024, Sage agreed to deliver up to 150 megawatts of new geothermal baseload power to Meta, the parent company of Facebook. At the time, the companies reported that the project's first phase would aim to be operating in 2027.

The company also raised a $17 million Series A, led by Chesapeake Energy Corp., in 2024.

Houston expert discusses the clean energy founder's paradox

Guest Column

Everyone tells you to move fast and break things. In clean energy, moving fast without structural integrity means breaking the only planet we’ve got. This is the founder's paradox: you are building a company in an industry where the stakes are existential, the timelines are glacial, and the capital requires patience.

The myth of the lone genius in a garage doesn’t really apply here. Clean energy startups aren’t just fighting competitors. They are fighting physics, policy, and decades of existing infrastructure. This isn’t an app. You’re building something physical that has to work in the real world. It has to be cheaper, more reliable, and clearly better than fossil fuels. Being “green” alone isn’t enough. Scale is what matters.

Your biggest risks aren’t competitors. They’re interconnection delays, permitting timelines, supply chain fragility, and whether your first customer is willing to underwrite something that hasn’t been done before.

That reality creates a brutal filter. Successful founders in this space need deep technical knowledge and the ability to execute. You need to understand engineering, navigate regulation, and think in terms of markets and risk. You’re not just selling a product. You’re selling a future where your solution becomes the obvious choice. That means connecting short-term financial returns with long-term system change.

The capital is there, but it’s smarter and more demanding. Investors today have PhDs in electrochemistry and grid dynamics. They’ve been burned by promises of miracle materials that never left the lab. They don't fund visions; they fund pathways to impact that can scale and make financial sense. Your roadmap must show not just a brilliant invention, but a clear, believable plan to drive costs down over time.

Capital in this sector isn’t impressed by ambition alone. It wants evidence that risk is being retired in the right order — even if that means slower growth early.

Here’s the upside. The difficulty of clean energy is also its strength. If you succeed, your advantage isn’t just in software or branding. It’s in hardware, supply chains, approvals, and years of hard work that others can’t easily copy. Your real competitors aren’t other startups. They’re inertia and the existing system. Winning here isn’t zero-sum. When one solution scales, it helps the entire market grow.

So, to the founder in the lab, or running field tests at a remote site: your pace will feel slow. The validation cycles are long. But you are building in the physical world. When you succeed, you don’t have an exit. You have a foundation. You don't just have customers; you have converts. And the product you ship doesn't just generate revenue; it creates a legacy.

If your timelines feel uncomfortable compared to software, that’s because you’re operating inside a system designed to resist change. And let’s not forget you are building actual physical products that interact with a complex world. Times are tough. Don’t give up. We need you.

---

Nada Ahmed is the founding partner at Houston-based Energy Tech Nexus.

Houston maritime startup raises $43M to electrify cargo vessels

A Houston-based maritime technology company that is working to reduce emissions in the cargo and shipping industry has raised VC funding and opened a new Houston headquarters.

Fleetzero announced that it closed a $43 million Series A financing round this month led by Obvious Ventures with participation from Maersk Growth, Breakthrough Energy Ventures, 8090 Industries, Y Combinator, Shorewind, Benson Capital and others. The funding will go toward expanding manufacturing of its Leviathan hybrid and electric marine propulsion system, according to a news release.

The technology is optimized for high-energy and zero-emission operation of large vessels. It uses EV technology but is built for maritime environments and can be used on new or existing ships with hybrid or all-electric functions, according to Fleetzero's website. The propulsion system was retrofitted and tested on Fleetzero’s test ship, the Pacific Joule, and has been deployed globally on commercial vessels.

Fleetzero is also developing unmanned cargo vessel technology.

"Fleetzero is making robotic ships a reality today. The team is moving us from dirty, dangerous, and expensive to clean, safe, and cost-effective. It's like watching the future today," Andrew Beebe, managing director at Obvious Ventures, said in the news release. "We backed the team because they are mariners and engineers, know the industry deeply, and are scaling with real ships and customers, not just renderings."

Fleetzero also announced that it has opened a new manufacturing and research and development facility, which will serve as the company's new headquarters. The facility features a marine robotics and autonomy lab, a marine propulsion R&D center and a production line with a capacity of 300 megawatt-hours per year. The company reports that it plans to increase production to three gigawatt-hours per year over the next five years.

"Houston has the people who know how to build and operate big hardware–ships, rigs, refineries and power systems," Mike Carter, co-founder and COO of Fleetzero, added in the release. "We're pairing that industrial DNA with modern batteries, autonomy, and software to bring back shipbuilding to the U.S."

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