Criterion Energy Partners is aiming to be a next-gen energy company. Photo via Getty Images

Sean Marshall and Danny Rehg founded Criterion Energy Partners in 2020 with the hope that geothermal energy could be the cleaner, safer wave of the future. Less than three years later, the team is close to making their plan a reality thanks to a geothermal well that they hope to drill this year.

Entrepreneurship wasn’t always part of the plan for either partner. When Marshall enrolled in the MBA program at Rice University’s Jones School of Business in 2016, he had a successful career at Credit Suisse and had his eye set on a future political career. But then he met classmate Rehg, whose background was in petroleum engineering. Their wives were both attorneys in the Houston district attorney’s office and the couples became fast friends. They also realized that, as Marshall now puts it, Rehg knew how to drill wells and he knew how to make deals.

In the ensuing years, both Rehg and Marshall's careers evolved and, eventually, the pair started looking for other opportunities. That’s when they read an article in Rolling Stone about geothermal energy.

“It was really a place where it really felt like this was something we were put here to do,” says Marshall.

Marshall and Rehg spent the ensuing months “like rats in a dumpster” learning about the players and opportunities in the geothermal industry and built from there. They learned about Pleasant Bayou Power Plant, a 1989 geothermal energy project based in Brazoria County that was backed by the U.S. Department of Energy.

Last summer, Criterion Energy Partners, a member of Greentown Houston, closed on a 10,000-acre lease around the site of Pleasant Bayou.

"We hope by the end of this year we will be generating electrons,” says Marshall.

Though the company has a patented technology that connects wells to the grid, called Criterion Geothermal System, Marshall says that some of the best advice he’s gotten was, “Don’t fall in love with your technology; fall in love with the problem.” The 2021 Texas freeze reminded the founders what that was.

“People were looking for cleaner, lower-emission power sources and [there was] a need for energy resiliency,” says Marshall, explaining that the freeze created an ideal situation for the company, as people began to think more outside the grid.

The year 2022 was a big one for Criterion Energy Partners. Oil and gas powerhouse Patterson-UTI invested in the company, followed by funding from the Department of Energy. The money not only allowed Criterion Energy Partners to lease their land, they are also now paying 12 salaries, including those of the founders. The team offices in The Cannon’s Esperson coworking space.

“Our mission is to make geothermal commercially viable everywhere,” says Marshall. “I still believe in that.”

However, Criterion Energy Partners may be even bigger than proving an alternative energy source. Marshall says that geothermal is the foundation on which they are building “a next-generation energy company.” Criterion Energy Partners could be the more stable basis for a whole new energy system.

Sean Marshall and Danny Rehg founded Criterion Energy Partners in 2020. Photos courtesy

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This article originally ran on InnovationMap.

Here's what startups took home wins at CERAWeek. Photo by Natalie Harms/InnovationMap

8 energy tech startups recognized at Houston's CERAWeek pitch competition

taking home the W

Over 200 startups participated in CERAWeek this year, and 18 of those companies pitched at a Greater Houston Partnership event.

The Houston Energy Transition Initiative, an initiative to promote Houston's work within the energy transition, hosted its second annual HETI Energy Ventures Competition at CERAWeek Innovation Agora. The competition was divided into four categories. The first batch of startups consisted of five companies from the Texas Entrepreneurship Exchange for Energy, or TEX-E, a collaboration with Greentown Labs, MIT’s Martin Trust Center for Entrepreneurship, and universities across Texas.

The winning startups shared $50,000 of prizes, sponsored by TEX-E. Houston-based Helix Earth Technologies — which has developed high-speed, high-efficiency filter systems derived from technology originating at NASA — won both the first place prize and fan favorite for the category. Helix's co-founders, Rawand Rasheed and Brad Husick from Rice University, walked away with $25,000 in prizes

Founded by Bryon Praslicka, Daniel Zamarron, and Craig Newman from Texas A&M University, Flux Works LLC, and its magnetic gear technology, took second place and $15,000 home. Tierra Climate, a two-sided marketplace for carbon offsets and other sustainability efforts founded by Emma Konet and Jacob Mansfield from Rice University, won third place and $10,000.

Helix Earth Technologies walked away with the top prize of the TEX-E category. Photo via greentownlabs.com

The next sets of startup pitches we broken down by funding stages — pre-seed and seed, series A, and series B and beyond.

Red Shift Energy, uses plasma energy to produce hydrogen from hydrogen sulfide, won fan favorite in the pre-seed and seed category sponsored by HX Venture Fund. A member of Halliburton Labs, the company also was recognized as Chevron favorite.

Per the judging panel, CanaGas won the title of most promising in the pre-seed and seed category sponsored by Alchemy Industrial. The Canadian company liquifies natural gas without costly cryogenics or stripping of the gas.

Houston-based Criterion Energy Partners won both the most-promising series A company category sponsored by SLB, but also the fan favorite series A category sponsored by Guerrella LLC. A geothermal energy tech company, Criterion was also a member of Rice's inaugural Clean Energy Accelerator cohort.

OptiSeis Solutions also won in both categories for the series B track. The company, a geophysical acquisition design and software company, won the title of most promising in the series B category sponsored by Pana LCE Investments and the series B fan favorite category sponsored by Halliburton Labs.

Lastly, the competition named the Most Impactful DEI, a category sponsored by Pana LCE Investments. Austin-based Gazelle Ecosystems, a social innovation startup with eco-solutions for corporations, won that category.

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This article originally ran on InnovationMap.

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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.