Ten climatetech startups were named most-promising at this annual Rice Alliance Energy Tech Venture Forum. Photo courtesy Rice Alliance.

Investors at the Rice Alliance Energy Tech Venture Forum have named the 10 most-promising startups among the group of 100 clean tech companies participating in the event.

The 22nd annual event was held yesterday, Sept. 18, at Rice University’s Jones Graduate School of Business and was part of the second Houston Energy and Climate Startup Week.

The most-promising startups will receive $7,000 in in-kind legal services from Baker Botts.

The 10 most-promising companies included:

  • Houston-based Xplorobot, which has developed laser gas imaging technology for the first handheld methane detection device approved by the EPA as an alternative test method
  • Seattle-based Badwater Alchemy, a desalination company that uses nano materials to purify saline water at a fraction of the cost of traditional methods
  • San Francisco-based Ammobia, which is developing a clean ammonia production process
  • Illinois-based Celadyne Technologies, which is building hydrogen for industrial decarbonization with durable and efficient fuel cells and electrolyzers
  • Massachusetts-based MacroCycle Technologies, which converts plastic waste in the form of bottles, food trays and polyester textiles into virgin-grade mPET resin
  • Massachusetts-based AtoMe, which uses nano-ceramics to develop ultra-durable metals for 3D printing
  • Colorado-based Advanced Thermovoltaic Systems (ATS) Energy, a renewable energy semiconductor manufacturing company
  • North Carolina-based Lukera Energy, which is converting waste methane into high-value fuel
  • Midland, Texas-based AI Driller, a company that uses AI and machine learning to enable remote operations and provide historical drilling data for survey management, anti-collision monitoring and iob reporting
  • New York-based Fast Metals Inc., which has developed a chemical process to extract valuable metals from complex toxic mine tailings that is capable of producing iron, aluminum, scandium, titanium and other rare earth elements using industrial waste and waste CO2 as inputs

Arculus Solutions won the People's Choice Award. The New Jersey-based company retrofits natural gas pipelines for safe hydrogen transportation. It also won Track A: Hydrogen, Fuel Cells, Buildings, Water, & Other Energy Solutions at the Energy Venture Day and Pitch Competition during CERAWeek earlier this year.

The 100 energy technology ventures selected to participate in the forum were named earlier this year. See the full list here.

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Hertha Metals raises $133M Series A round, plans high-purity iron plant

cleaner steel

Conroe-based Hertha Metals has closed a $133.65 million Series A round that includes a $65 million equity investment from the Pentagon. The startup uses a one-step process to convert iron into molten steel or high-purity iron.

Khosla Ventures and Doerr Capital co-led the round, with participation from CEV, Pear Ventures, Gates Frontier, Niterra SUISO no MORI Fund, Toyota Ventures, and Siemens Financial Services.

The federal investment came from the U.S. Department of Defense’s Industrial Base Analysis and Sustainment program. The program aims to strengthen and modernize the U.S. Defense Industrial Base, a network that researches, designs, builds, and maintains military weapons, equipment, technology, and services.

The Series A funding will finance construction of Hertha Chalyx, a plant that will be capable of producing 10,000 metric tons of steel-grade and magnet-grade high-purity iron.

Hertha says Chalyx will provide U.S.-made material for manufacturers of rare-earth magnets. Today, China controls more than 90 percent of the global manufacturing of rare-earth magnets.

Rare-earth magnets can be found in fighter jets, smart bombs, submarines, satellites, drones and other military hardware. These magnets are also key components in electric vehicle motors, wind turbines, computer hard drives, smartphones, headphones, cordless tools and an array of other products.

“Every electric vehicle, aerospace platform, radar system, and data center depends on domestic iron and magnet feedstock suppliers,” Laureen Meroueh, founder and CEO of Hertha, said in a press release.

“Hertha Chalyx closes that gap,” she added. “We are building the supply chain this country needs, and we are doing it by providing a domestic cost-competitive option for manufacturers while unlocking safer and cleaner production.”

Hertha says Chalyx, alongside its Pi100 pilot project, will be the first modern-day “iron and steel innovation complex.” The startup expects to break ground on Chalyx this year.

Since its founding in 2022, Hertha has raised more than $150 million from investors.

This spring, Hertha led the manufacturing category on Fast Company’s list of the World’s Most Innovative Companies of 2026.

3 must-know fall application deadlines for Houston energy innovators

Editor's note: As fall reaches full swing, Houston's innovation and cleantech scene is calling on the latest batch of founders and startups looking to make a difference. A number of accelerators have opened applications. Read below to see which might be a good fit for you or your venture. And take careful note of the deadlines. Please note: this article may be updated to include additional information and programs.

Did we miss an accelerator or competition accepting applications? Email innoeditor@innovationmap.com for editorial consideration.

Greentown Lab's Go Make 2027: Advanced Carbon Materials with ExxonMobil

Deadline: Oct. 9

Details: Greentown Labs is seeking applications from startups developing novel carbon-based technologies for its latest Go Make cohort in conjunction with ExxonMobil. The structured accelerator is designed to facilitate validation activities and explore potential long-term collaborations with Exxon, according to Greentown. Founders will have the opportunity to engage directly with industry leaders to test, validate and scale their carbon technologies in real commercial contexts. The program tentatively starts on Jan. 20, 2027 and concludes June 16, 2027. Find more information here.

Activate's U.S. Fellowship Cohort 2027

Deadline: Oct. 30

Details: Activate supports scientists at "the outset of their entrepreneurial journey." It partners with U.S.-based funders and research institutions to support its fellows in developing high-impact technology. Its fellows receive a living stipend, research and development funding, connections from Activate's robust network of mentors and access to a curriculum specific to the program for two years. Applicants must have a bachelor’s degree and 4-plus years of post-baccalaureate scientific research, engineering or technology development experience. Their work must be based in the physical or biological sciences or related engineering disciplines. Find more information here.

Rice Innovation Fellows

Deadline: Oct. 30

Details: The Liu Idea Lab for Innovation and Entrepreneurship (Lilie)'s Rice Innovation Fellows program supports Rice Ph.D. students and postdocs in turning their research into real-world ventures. Participants receive $10,000 in translational research funding, co-working space and personalized mentorship. Candidates from all Rice engineering and science-related disciplines are encouraged to apply. Find more information here.

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A version of this article originally appeared on our sister site, InnovationMap.

Houston carbon removal company secures $35M in financing

national scale

Houston-based Vaulted Deep, a waste management and carbon removal company, has announced a major $35 million debt facility from Italian investment bank Mediobanca to support its national expansion.

U.K.-based market energy solutions CFP Energy arranged the deal, which is “the largest publicly disclosed U.S. commercial debt deal in durable carbon removal to be secured by long-term purchase contracts,” according to a news release from the companies.

The financing will support new waste disposal sites for Vaulted Deep and advancements of the company’s AI-enabled site development platform. The platform helps identify locations, navigate permitting and optimize injection operations. When candidates are looking for sites, the platform will pull from regulatory, geology and waste-supply data to assist, which Vaulted Deep says will help streamline the permitting process. After the site is operating, the platform helps control algorithms to maximize safe disposal capacity and monitor the process along the way.

"Waste operators across the country need new options as traditional disposal options become limited,” Julia Reichelstein, CEO and co-founder of Vaulted Deep, said in the release. “This financing lets us take on more projects and invest in the tools that help us evaluate and develop new sites faster. This is a meaningful milestone for Vaulted as we move into the next phase of building infrastructure at a much larger scale."

The deal is supported by Vaulted Deep's long-term waste service and carbon removal purchase contracts. The company says it delivered more than 20,000 tons of carbon removal to buyers in the first half of 2026, which is more than it delivered in all of 2025.

"By facilitating these types of transactions, we connect institutional capital with innovative climate technologies, helping accelerate the deployment of high-integrity carbon removal solutions,” Tyler Manchester, head of voluntary carbon for CFP Energy, added in the release. “It reflects growing investor confidence in these solutions, driven by rising demand from corporate buyers seeking permanent pathways to support net-zero commitments and long-term climate strategies."

Beyond the facility, Vaulted Deep has secured $48 million in equity financing in addition to its $8 million from the XPRIZE Carbon Removal competition, backed by Elon Musk’s charitable organization, The Musk Foundation.

The company's well injection technology is used to store organic waste deep underground in stable geologic formations. In 2025, it inked a 12-year deal with Microsoft to remove up to 4.9 million metric tons of carbon dioxide from the environment.