New global report names top cleantech startups to keep an eye on

seeing green

Fervo Energy — and a few other Greentown Labs companies — made a global list of clean tech companies. Photo via fervoenergy.com

Nine Greentown Labs members were recognized on a global list honoring cleantech companies.

Houston-based Fervo Energy was named to Cleantech Group’s Global Cleantech 100 report. Cleantech Group is a research-driven company that aids the public sector, private sector, investors, and also identifies, assesses, and engages with the innovative solutions around climate challenges.

Fervo, a geothermal energy company that specializes in a renewable energy technology that uses hot water to produce electricity, debuted in 2022 on the list, and was honored in the “Energy & Power” category for the second straight year.

The other Greentown Labs, which is dual located in Houston and Somerville, Massachusetts, companies recognized on the list include:

Amogy, a New York-based novel carbon-free energy system using ammonia as a renewable fuel
Carbon Upcycling Technologies, a Canadian waste and carbon utilization company
Dandelion Energy, New York-based company offering ground source heat pumps for most homes
Energy Dome, a Milan-based company addressing the problem of long-duration energy storage
e-Zinc, a Canadian company with a breakthrough electrochemical technology for energy storage
Nth Cycle, a Massachusetts company with sustainable metal refining
Raptor Maps, a Massachusetts company with a software platform for solar assets' performance data management
Sublime Systems, a Massachusetts companydeveloping a breakthrough process for low-carbon cement
WeaveGrid, a California company working with utilities, automakers, EVSEs, and EV owners to enable and accelerate the electrification of transportation

The number of nominations from the public, a panel, i3, awards and Cleantech Group totaled 25,435 from over 65 countries, which is a 61% increase from the 2023 nomination process. Winners were chosen from a short list of 330 companies by a panel of over 80 industry experts.

While not on the list, Beaumont-based Fortress Energy was mentioned for its electrolyzer supply agreement with Cleantech Group 100 winner Electric Hydrogen.

The Cleantech Group 100 was started 15 years ago.

“In 15 more years, we will be at 2039—by which time, a mere decade out from the ‘net-zero’ target of 2050,” Cleantech Group CEO Richard Youngman says in the report. “I would expect the composition of our annual list to have markedly changed again, and the leading upcoming private companies of that time to reflect such.”

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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."

Shell partners with UK-based co. for hydrogen electrolyzer pilot

ultra-efficient electrolyzer

Shell Global Solutions International, a subsidiary of Shell, which maintains its U.S. headquarters in Houston, has signed a collaboration agreement with London-based Supercritical Solutions to advance Supercritical’s ultra-efficient hydrogen electrolyzer technology toward a field pilot demonstration.

In the deal, the companies will collaborate on a paid technology feasibility study that will support the evaluation and planning of the pilot demonstration, according to a news release. Supercritical Solutions’ technology aims to deliver high-efficiency renewable hydrogen at a lower cost for the industrial hydrogen market.

"Signing this collaboration agreement with Shell is a major milestone for Supercritical Solutions and an important step on our commercialisation journey,” Luke Tan, co-founder of Supercritical, said in the news release. “We are directly addressing the cost and complexity barriers facing the renewable hydrogen market. We are excited to move forward with a company like Shell, whose global leadership has been proven to accelerate innovative technologies to market.”

Supercritical’s hydrogen electrolyser technology can operate at high temperatures and pressures of up to 220 bar without the need for an external hydrogen compressor, rare-earth materials or easily degradable membranes. The technology removes the typical compression step in the process while delivering hydrogen at industry standards. It requires significantly less energy than many traditional electrolyzers and is more cost-efficient.

This recent investment builds on an ongoing relationship between Shell and Supercritical. Supercritical was founded in 2020 and was runner-up in Shell’s New Energy Challenge, which helps startups and scaleups develop sustainable technologies, in 2021. Shell Ventures then invested in Supercritical’s Series A funding round in 2024 with Toyota Ventures.

3 Houston-area companies named to Global Cleantech 100

Energized

Three Houston-area companies—Amperon, Hertha Metals and Vaulted Deep—appear on this year’s Global Cleantech 100 list.

The unranked list, generated by market intelligence and advisory firm Cleantech Group, identifies the 100 privately held companies around the world that are most likely to make a significant impact in the cleantech market over the next five to 10 years.

For the 2026 list, Cleantech Group received more than 24,000 Global Cleantech 100 nominations from nearly 60 countries. Cleantech Group scored those companies and narrowed the contenders to 264. An expert panel reviewed those nominees, and the list was whittled down to the 100 winners.

Here’s a rundown of the three Houston-area honorees:

Amperon

Founded in 2018 by Sean Kelly and Abe Stanway, Houston-based Amperon offers an AI-enabled energy forecasting and analytics platform designed to help stabilize electric grids. Amperon received undisclosed amounts of venture capital from National Grid Partners and Tokyo Gas Co. Ltd. last year and announced a recent investment from Samsung Ventures earlier this month.

Hertha Metals

Founded in 2022 by Laureen Meroueh, Conroe-based Hertha Metals provides a single-step process for producing sustainable steel. Last year, the company emerged from stealth mode and raised more than $17 million in venture capital.

Vaulted Deep

Vaulted Deep’s technology injects excess organic waste underground to remove carbon dioxide from the atmosphere. Julia Reichelstein and Omar Abou-Sayed founded the Houston-based company in 2023. Last year, the startup raised $32.3 million in venture capital. Also in 2025, Vaulted Deep signed a 12-year deal with software giant Microsoft to remove up to 4.9 million metric tons of carbon dioxide from the environment.

Vaulted Deep also made the list last year, along with Houston-based Syzygy Plasmonics and Fervo Energy. Fervo was also named the 2025 North American Company of the Year by Cleantech Group.

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