Energy & Power is the largest category on this year’s list with 17 companies, followed by Materials & Chemicals (15), Resources & Environmental Management (9), Waste & Recycling (4), Agriculture & Food (3), and Transportation & Logistics (2).
What’s Driving This Year’s List
Powering the AI Revolution – AI remains the clearest demand driver in cleantech, but 2026 brought new clarity on where customers are actually willing to pay: power access and speed-to-power. Geothermal emerged as a standout following Fervo’s IPO in May, and this year’s list includes Telura (Germany), TerraFerno Geothermal Solutions (Canada), and Enerdrape (Switzerland), each tackling a different part of the geothermal value chain.
With more than $260 billion worth of data centers cancelled due to local opposition (Heatmap) in the U.S. ahead of the midterms, grid flexibility has become a workaround to lengthy interconnection queues—and a hedge against ratepayer backlash. Pado AI, Cellect Energy, Anode Technology, and Alderbuck Energy each address a different layer of that flexibility stack, while Ferveret’s adaptive-phase liquid cooling targets the efficiency metric that finally got a consensus name this year: “tokens per watt.” Aslan Renewables and Squid unlock capacity from existing resources, and Aqua-Cell Energy and FeX Energy bring two contrasting approaches to long-duration storage.
The Race for Mineral and Material Independence – At least eight companies on this year’s list are attacking the critical minerals and refining challenge, spanning lithium, copper, rare earths, graphite, and gallium. They include REEgen, ChemFinity Technologies, Thunderstone, Green Graphite Technologies, and Recupere Metals, alongside Supra Elemental Recovery, which extracts gallium and scandium from industrial waste streams. DexMat is pursuing a different route entirely: a carbon nanotube material designed to replace copper.
Extreme Heat Resilience Comes of Age – Coming off a summer of punishing heat waves across Europe, Cleantech Group expects 2027 to be the year extreme heat resilience becomes a category of its own. SkyCool Systems and Evercloak are cutting the energy cost of cooling, while FireSwarm Solutions and Voxelis AI target wildfire suppression at the peak-burn stage. Water scarcity is a growing part of the story too, with three desalination innovators on the list: Cetos Water, Harmony Desalting, and Waterwhelm.
Also on the List – The 2026 honorees extend well beyond these themes, from heavy-industry decarbonization (CURA, Litherm, Perocycle) and AI-driven materials discovery (Level Nine, Mater-AI, Polygence Future) to precision agriculture (Braintree Technologies, CroBio, Prospect Growth) and maritime carbon capture (Seabound).
Looking Ahead
This year’s honorees show that even in a year of geopolitical shocks and cautious capital, innovation is finding its footing where security and resilience meet. From geothermal drilling and grid flexibility to critical mineral recovery and desalination, the 2026 Cleantech 50 to Watch points to the technologies most likely to define the next wave of cleantech growth.
“We extend our congratulations to the winners of the 2026 Cleantech 50 to Watch list,” said DeOrsey, “and thank the many expert panelists who contributed nominations and votes this year.”
Download your complimentary copy of the 2026 Cleantech 50 to Watch, which includes links to all the companies mentioned above.
About Cleantech Group
Cleantech® Group is the human intelligence authority on global cleantech innovation. Since 2002, we’ve helped decision-makers across industry, finance, and policy navigate the rapid shifts transforming the global economy. We go beyond market intelligence — offering insights, strategic guidance, and curated connections to help leaders stay ahead, identify opportunities, and act with confidence. Our insight is built on over 20 years of human intelligence, proprietary data, and direct relationships with the ecosystem leaders driving change.