Climate Tech Startups 2026: Firm Power and Storage Draw Investors

The short answer: the leaders are building infrastructure

Ask who the top climate tech startups are in late 2026 and you get very different lists depending on who you ask. One group of rankings rewards software and measurement tools. Another rewards companies that pour concrete, run factories and sign contracts measured in gigawatt-hours. The money in 2026 points to the second group. The companies that matter most right now are the ones selling firm power and storage to a grid under pressure from AI data centers.

One ranking puts Redwood Materials first, followed by Form Energy and TerraPower, with Base Power and Antora Energy close behind. It argues that factories, contracted capacity and repeat installations now say more about a company than a big funding round does14. A list of US startups built on different criteria starts with KoBold Metals, Watershed and Base Power, and gives more room to carbon-removal and carbon-credit companies like Heirloom, Charm Industrial and Sylvera15. A list focused on AI includes Watershed, Emerald AI and Fervo Energy, separating companies where AI is the product from those where it supports physical engineering13. The names change from list to list, but storage, geothermal and battery materials keep showing up.

The money followed the power shortage

The funding numbers explain why. Currence, formerly Sightline Climate, says climate tech venture investment hit $26.1 billion in the first half of 2026, up 55% from a year earlier and the strongest first half since 20223. Most of that growth came from one place. Low-carbon data center developers took 34% of all climate funding in the half, compared with 3% a year earlier3. Two deals, DayOne at $4.5 billion and Nscale at $2 billion, made up about a quarter of the total10.

Trackers don't agree on whether this is a real recovery. Net Zero Insights puts private-market climate tech at $41.3 billion for the half, close to the $43.6 billion of a year earlier10. In that view the market didn't grow. It just shifted into fewer, bigger deals. Deal counts support that reading: they fell 25% year over year to a five-year low, and the ten biggest deals took 42% of funding2. In the third quarter, Net Zero Insights recorded equity up 17% to $15.8 billion, with every stage growing, but only 686 deals, the fewest since 20211.

The takeaway is that capital has come back, but only for a narrow set of companies. Fusion, fission, geothermal and storage raised about $6.3 billion across 17 rounds in the third quarter. That included three $1 billion rounds, for Commonwealth Fusion Systems, Valar Atomics and Base Power1. Founders outside those areas are dealing with a much tighter market than the headline figures suggest.

Grid-scale storage is now about execution

Form Energy shows most clearly how storage has changed. Its iron-air batteries are built to discharge for 100 hours. In February 2026 it signed a definitive agreement for a 300 MW / 30 GWh system to power a Google data center in Pine Island, Minnesota, which has been described as the largest storage project announced worldwide by energy capacity24. Google's commitment has been put at about $1 billion, and it marks a move from venture rounds and government grants toward a large customer paying directly for reliable power27. Form has also expanded into Europe with a 10 MW / 1,000 MWh project in Ireland due online by 202924. One ranking estimates Form's commercial backlog at about 80 GWh and says the open question is whether its manufacturing can keep up14.

The technology has known weaknesses. One analysis puts round-trip efficiency at roughly 40%, a cost buyers seem willing to accept for cheap long-duration storage. It describes the main risk now as building and deploying at scale, not whether the technology works27. That judgment fits the data: utility resource plans and hyperscaler contracts are not signed for laboratory curiosities.

Competitors are arriving. Amsterdam-based Ore Energy raised a $43 million Series A in August to build what it calls Europe's first iron-air battery factory, bringing its total to about $61 million23. It has a 1 GWh deal with Dutch supplier Budget Thuis, with the first 400 MWh due in 202830. It argues that a fully European supply chain gives it an edge over Form29. In India, Meine Electric raised a $750,000 pre-seed round for 16–24 hour iron-air systems26. Iron-air is turning into a category, not just one company.

Sodium-ion is the other chemistry to watch. GM is developing a new sodium-ion chemistry with startup Peak Energy for grid storage. Because the cells run with less overheating risk, Peak's design leaves out cooling and fire-suppression systems28. In July, Peak announced a $71 million factory near Sacramento that can make 4 GWh of sodium-ion batteries a year21. Earlier US sodium-ion efforts failed, so a large automaker's backing matters here21.

EV batteries are getting a second life

Redwood Materials tops at least one ranking because much of its operating risk is already behind it. It takes in more than 20 GWh of lithium-ion batteries a year, produces more than 60,000 metric tons of critical materials, and says it recovers over 95% of the lithium, nickel, cobalt and copper14. Its newer business, reusing old EV packs as stationary storage before recycling them, links EV batteries to the grid. Redwood runs a 12 MW / 63 MWh microgrid of second-life packs at a Crusoe data center in Nevada, and GM has about 10,000 packs headed its way28.

Next-generation cells are less proven. Group14 Technologies has silicon-anode material in mass-produced batteries and a factory of roughly 10 GWh ramping up, but it still has to win enough EV programs to fill that capacity14. Investors clearly favor the supply chain: seven of the 25 most-funded climate startups work in battery materials, recycling or manufacturing20.

Carbon capture is still small and depends on policy

Carbon capture is the one area where the rankings and the money don't line up. About $3.6 billion has gone into carbon-removal startups since 2021, and Climeworks accounts for roughly a quarter of it31. The economics still rest on the 45Q tax credit, which pays $85 a ton for industrial capture and $180 a ton for direct air capture31. The industry has reached real scale in places. Occidental's 1PointFive started up its Stratos facility, built to capture 500,000 tonnes a year, in March 202636.

Trackers disagree about where venture funding for direct air capture is heading. Tracxn found an 84% year-over-year drop in early 202639. Another analysis calls the funding erratic rather than dead, pointing to Carbonology's roughly $18.45 million Series A in the second quarter35. Both can be true. Big checks have dried up, while mid-sized rounds for CO2 utilization, mineralization and wastewater-based removal have kept the sector going35. The carbon-removal market still relies mostly on Series A rounds, and the shortage of later rounds is a warning sign34.

Even basic facts vary between lists. One ranking describes Heirloom as spreading crushed rock on farmland and says it has raised $53 million15. Deal trackers describe Heirloom's technology as limestone-based direct air capture and record a $150 million round in December 202434, and another estimate puts its total at more than $500 million31. The deal records are the more reliable version, and readers should treat polished startup lists with caution.

Clean energy breakthroughs: geothermal goes public, fusion keeps raising

Geothermal had the year's biggest exit. Fervo Energy's IPO has been reported as raising $1.9 billion, with shares up 35% on debut13. Other coverage describes the same deal as a listing valued at about $1.9 billion8, so the exact figure depends on the source. Either way, investors had singled out Fervo as the likeliest climate IPO of 20264, and X-Energy's roughly $1 billion nuclear IPO showed the window had reopened3. Quaise Energy raised $134 million to drill for superhot rock using millimeter waves5, and Critical Energy raised $22 million for modular geothermal turbines9.

Fusion is attracting large checks long before any commercial power exists. Proxima Fusion's roughly $468 million round, backed by RWE and Google, valued it at €2.4 billion, with a demonstration plant targeted for the mid-2030s5. Helion was listed as the most valuable climate startup at $15.5 billion18. Its next step is producing commercial electricity on a very fast timeline, with Microsoft signed up for at least 50 MW14.

The verdict

The climate tech companies with momentum in 2026 can deliver electrons or molecules on a contract. Form, Redwood, Base Power, Antora and Fervo stand out because each has moved from pilots to large-scale deployment, often with a tech company as the customer. The risk is that the sector now depends heavily on AI data center demand. Investors have already said that if the AI bubble bursts, energy could suffer with it4. For now, the companies attracting the most money are the ones that help data centers get power quickly.