Six companies have joined Greentown Houston, focused on long-duration energy storage systems, 3D solar towers and more. Photo courtesy Greentown Labs.

Greentown Labs announced the six startups to join its Houston community in Q2 of 2025.

The companies are among a group of 13 that joined the climatetech incubator, which is co-located in Houston and Boston, in the same time period. The companies that joined the Houston-based lab specialize in a number of clean energy applications, from long-duration energy storage systems to 3D solar towers.

The new Houston members include:

  • Encore CO2, a Louisiana-based company that converts CO2 into ethanol, acetate, ethylene and other sustainable chemicals through its innovative electrolysis technology
  • Janta Power, a Dallas-based company with proprietary 3D-solar-tower technology that deploys solar power vertically rather than flatly, increasing power and energy generation
  • Licube, an Austin-based company focused on sustainable lithium recovery from underutilized sources using its proprietary and patented electrodialysis technology
  • Newfound Materials, a Houston-based company that has developed a predictive engine for materials R&D
  • Pix Force, a Houston-based company that develops AI algorithms to inspect substations, transmission lines and photovoltaic plants using drones
  • Wattsto Energy, a Houston-based manufacturer of a long-duration-energy-storage system with a unique hybrid design that provides fast, safe, sustainable and cost-effective energy storage at the microgrid and grid levels

Seven other companies will join Greentown Boston's incubator. See the full list here.

Greentown Houston also added five startups to its local lab in Q1. Read more about the companies here.

Greentown Labs and MassChallenge have formed a strategic partnership. Photo courtesy Greentown Labs.

Greentown Labs combines forces with MassChallenge to support more climate startups

strategic partnership

Climatetech incubator Greentown Labs has formed a strategic partnership with global zero-equity accelerator MassChallenge.

The two organizations have headquarters in the Boston area, while Greentown Labs is also co-located in Houston. MassChallenge has a hub in Dallas, as well as others in Israel, Switzerland and the United Kingdom.

The new partnership aims to strengthen the ecosystem for early-stage climatetech startups by providing more mentorship, support and a broader commercialization network for members, according to a news release.

Greentown Labs will share its expertise with the 23 startups in MassChallenge's first climate-specific accelerator, known as the MassChallenge Early Stage Climate program. Additionally, Greentown Labs members will benefit from MassChallenge's network of expert mentors, judges, entrepreneurs, partners, investors, philanthropists and others.

“There are so many synergies and shared values between MassChallenge and Greentown that launching a collaboration like this feels like a natural next step for our organizations as we strive to support as many early-stage climate founders as possible,” Georgina Campbell Flatter, Greentown Labs CEO, said in the news release. “We want to reduce the friction and barriers to market for these climate entrepreneurs and ultimately increase their opportunity for success—ecosystem collaboration is an essential part of solving these challenges together.”

Combined, Greentown and MassChallenge report that they have supported more than 4,500 founders and more than 1,000 climate startups. MassChallenge has awarded more than $18 million in equity-free grants to startups, which have gone on to raise over $15 billion, since it was founded in 2009. Greentown Labs has helped more than 575 startups raise more than $8.2 billion in funding since it launched in 2011.

Greentown recently added five startups to its Houston community and 14 other climatetech ventures to its Boston incubator. It also announced its third ACCEL cohort, which works to advance BIPOC-led startups in the climatetech space, earlier this year. Read more here.

Five companies have joined Greentown Labs Houston, specializing in various "green" applications, from converting plastic waste into sustainable materials to developing energy-storage solutions. Photo courtesy Greentown Labs.

Greentown Labs announces newest startups to join Houston climatetech incubator

green team

Greentown Labs announced that it added five startups to its Houston community in Q1 of 2025.

The companies are among a group of 19 that joined the climatetech incubator, which is co-located in Houston and Boston, in the same time period. The companies that joined the Houston-based lab specialize in a number of "green" applications, from converting plastic waste into sustainable materials to developing energy-storage solutions.

The new Houston members include:

  • Concept Loop, a project of Pakistan-based Innova8e Inc., aims to repurpose post-industrial and post-consumer plastic waste into sustainable building materials.
  • GeoFuels, a Sugar Land-based company that produces hydrogen by using baseload geothermal power and methane pyrolysis.
  • PLASENE, a Houston-based company with an innovative platform that converts plastic waste into liquid fuel and low-carbon hydrogen through its proprietary catalysts and modular, scalable, pre-engineered units platform. The company was named to Greentown's ACCEL Year 3 cohort earlier this year.
  • RepAir Carbon, an Israeli company with a fully electric, zero-heat carbon-removal technology that consumes minimal energy, operates without liquids or solvents, and produces no hazardous materials or waste.
  • RotorVault from Pasadena, California, is commercializing energy-storage and load-following solutions that are containerized, modular, and field-deployable systems built on flywheel technology.

Fourteen other companies will join Greentown Boston's incubator. See the full list here.

PLASENE and five other new members—Thola, Respire Energy, Andros Innovations, FAST Metals and Tato Labs—join Greentown Labs through its most recent Advancing Climatetech and Clean Energy Leaders Program, or ACCEL, cohort. ACCEL, which works to advance BIPOC-led startups in the climatetech space, announced its third cohort last month.

From potato-starch-based bioplastics startups to companies developing carbon-coated silicon anodes, here's who's joining Greentown Labs and Browning the Green Space's ACCEL program. Photo via browningthegreenspace.org

2 Houston startups join Greentown Labs' BIPOC-led accelerator program

seeing green

Greentown Labs and Browning the Green Space announced the newest cohort for its Advancing Climatetech and Clean Energy Leaders Program, or ACCEL, which works to advance BIPOC-led startups in the climatetech space.

Two Houston companies and one from Austin are among the eight startups to be named to the 2025 group.

“The startups selected for the third ACCEL cohort represent a phenomenal range of energy and climatetech innovations, which underscores our belief that everyone and many solutions must play a role in our community’s collective decarbonization efforts,” Georgina Campbell Flatter, Greentown’s new CEO, said in a release. “We’re proud to welcome these entrepreneurs to our community and eager to see all they’ll achieve throughout the program and beyond!”

Each of the early-stage startups within the cohort will receive $25,000 in non-dilutive grant funding and participate in the year-long program focused on product and technology development, market development, fundraising and management, and team development, according to Greentown. The curriculum is led by VentureWell, a nonprofit with expertise in venture development in climatetech.

The Houston companies include:

  • Carbonext, founded by Olanrewaju Tanimola. The company is leveraging its proprietary, off-the-shelf 3D-graphene technology to develop integrated solutions with carbon-coated silicon anodes to address challenges in the graphite ecosystem, as well as lithium-battery anodes.
  • PLASENE, founded by Sohel Shaikh, Alper Gulludag and Romolo Raciti. The company offers an innovative platform that converts plastic waste into liquid fuel and low-carbon hydrogen through its proprietary catalysts and modular, scalable, pre-engineered units

The remaining six companies are:

  • Inductive Robotics, founded in Austin by Madhav Ayyagari and David Alspaugh. The startup deploys autonomous robots that deliver EV charging directly to parked vehicles in commercial parking facilities, using a subscription-based model.
  • Andros Innovations, founded in Cambridge, Massachusetts by Laron Burrows. The startup has developed a reactor that produces ammonia more cheaply, cleanly and safely than traditional methods do.
  • FAST Metals, founded in Worcester, Massachusetts by Sumedh Gostu and Anthony Staley. It has developed a hydrometallurgical-recovery process capable of extracting iron, aluminum, scandium, titanium, and other rare-earth elements from industrial tailings.
  • Respire Energy, founded in Boston by Dave Hsu, Xiaowei Teng, and Candy Wong. The energy storage startup has developed a safe, low-cost, and long-duration metal-air battery designed for microgrids.
  • Tato Labs, founded in Brooklyn by Mecca McDonald and Mia Dunn. It is developing scalable, innovative, bioplastic products and packaging solutions that leverage potato starch, protect and preserve the natural ecosystem, and minimize plastic waste.
  • Thola, founded in Portland, Maine, by Nneile Nkholise and Lerato Takana. The company provides an on-demand marketplace for commercial-building sustainability and safety management, with a mission to decarbonize old buildings.

ACCEL is supported by the Massachusetts Clean Energy Center (MassCEC), Shell, Equinor, the Growth Capital Division of MassDevelopment, Microsoft and the Barr Foundation.

The accelerator has supported 13 early-stage startups since it was founded in 2023, resulting in $325,000 in grant funding. Houston companies have been represented in each cohort. Click here to see the 2024 cohort and here to see the inaugural 2023 cohort.

A mix of public and private investors have funded Greentown Labs. Photo via GreentownLabs.com

Investors from Houston and Boston fuel Greentown with $4M commitment

next era

Greentown Labs, a climatetech incubator with locations in the Houston and Boston areas, has announced it has received funding from a mix of investors.

The $4 million in funding came from both of the Houston and Massachusetts locations. Houston investors included Bobby Tudor, CEO of Artemis Energy Partners and chairman of the Houston Energy Transition Initiative; David Baldwin, co-founder of OpenMinds and TEX-E and partner at SCF Partners; and Rice University. Other investors included MassDevelopment and the City of Somerville.

“The challenges of the energy transition are immense, and the role played by technology incubators like Greentown Labs is essential,” Tudor says in a news release. “We believe this role, which is a partnership between academia, industry, philanthropists, entrepreneurs, and governments, is the best way to get to effective, scalable solutions in a time frame that the urgency of the challenge requires. We need all hands on deck, and this partnership between Massachusetts and Texas can be a role model for others.”

According to Greentown, the funding will support its financial position and contribute to preparing the incubator for its next chapter of supporting its its leadership team prepare for Greentown’s next chapter supporting and growing its 575 startups.

“Greentown’s mission aligns closely with the Houston Energy Transition Initiative’s goal of accelerating global solutions to address the dual challenge of meeting growing energy demand globally while also significantly reducing CO2 emissions,” adds Steve Kean, president and CEO of the Greater Houston Partnership.

With the announcement of the funding, Greentown named its board members, including Tudor, who will serve as Greentown Labs Board Chair. The other Houston-based board members are:

  • David Baldwin, co-founder of OpenMinds and TEX-E; partner atSCF Partners
  • Bob Harvey, former president and CEO of GHP; board member of TEX-E
  • Jane Stricker, senior vice president of energy transition and executive director of HETI

“With this new funding, Greentown is poised to expand its impact across its existing ecosystems and support even more climatetech startups,” adds Kevin Dutt, interim CEO of Greentown Labs. “We believe in the essential role entrepreneurship will play in the energy transition and we’re grateful for the support of our partners who share in that belief and our collective commitment to commercializing these technologies as quickly and efficiently as possible.”

According to Greentown, the incubator plans to announce its new CEO in the coming months.

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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.

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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."