Climate Tech Startups: The Leading Private Companies in 2026

Climate technology covers companies that cut greenhouse gas emissions or help the world adapt to a warming climate: clean power, energy storage, electric transport, low-carbon materials, carbon removal and the software that manages them. After a boom in 2021 and a sharp correction, climate tech has been reshaped by a new force: the electricity demand of AI data centres. This guide covers the private climate tech companies in our database, explains which technologies are attracting capital, and looks at the policy and market forces shaping the sector.

Every company links to a full profile with sources, funding and investors. Several important climate companies have recently gone public, such as Fervo Energy, the geothermal developer that listed in 2026, and are mentioned for context.

The companies

Fusion energy

Fusion, the process that powers the sun, promises abundant carbon-free electricity with little long-lived waste. Private fusion companies have raised billions of dollars. Commonwealth Fusion Systems, spun out of MIT, is building SPARC, a compact tokamak using high-temperature superconducting magnets, and plans a power plant in Virginia; Google has agreed to buy power from it. Helion Energy, valued at US$15.5 billion after a June 2026 round, uses a different pulsed approach that aims to capture electricity directly, and has agreed to supply Microsoft from 2028. No fusion device has yet produced net electricity, so these are high-risk, high-reward bets on technology that could transform energy if it works.

Batteries and energy storage

Redwood Materials, founded by Tesla co-founder JB Straubel and valued at about US$6 billion, recycles lithium-ion batteries into battery materials and, through Redwood Energy, repurposes used EV batteries as low-cost storage for data centres and the grid. Energy storage has become essential as solar and wind supply more power, because it shifts electricity from times of surplus to times of demand. Battery prices have fallen dramatically, making storage projects economic in many markets.

Low-carbon materials

Cement and steel production together account for a large share of global emissions. Canada's CarbonCure injects captured carbon dioxide into concrete, where it mineralises and strengthens the material, letting producers cut cement use and emissions. Its technology is installed at hundreds of concrete plants. Other startups are developing green steel, low-carbon cement and alternative materials.

Software for emissions and energy

Companies need to measure, report and reduce emissions to meet regulations and investor expectations. Validere, based in Canada, provides software for energy companies to track emissions and measure product quality across their operations. Carbon accounting and energy management software is a growing category as reporting requirements tighten in Europe and elsewhere.

AI's energy demand reshapes climate tech

AI data centres need enormous amounts of reliable electricity, and demand forecasts have risen sharply. Technology companies have committed to running on clean energy, so they are signing deals with nuclear plants, geothermal developers, fusion companies and storage providers. Crusoe, which began by using stranded natural gas to power computing and now builds large AI data centres, sits at the intersection of energy and AI infrastructure. Microsoft's agreement with Helion, Google's deals with Commonwealth Fusion Systems and Fervo, and Redwood's storage project for a Crusoe data centre show how AI demand is creating customers for climate technologies that previously struggled to find buyers. Our guide to AI infrastructure companies covers the computing side.

How climate tech funding has changed

Venture investment in climate tech surged in 2021, then fell as interest rates rose, some high-profile companies failed and policy uncertainty grew. Electric vehicle startups and some battery makers struggled, and several companies that listed through SPACs lost most of their value. Capital has since concentrated in technologies with clear customers, such as firm clean power for data centres, grid infrastructure and storage. Large rounds have increasingly come from growth investors, infrastructure funds and strategic corporate investors rather than early-stage venture capital alone.

Policy

Government policy strongly affects climate tech. In the United States, the Inflation Reduction Act of 2022 created large tax credits for clean energy, batteries and manufacturing; later changes under a new administration reduced or phased out some incentives, especially for electric vehicles and wind and solar, while support for nuclear, geothermal and some other technologies remained. The EU's emissions trading system and carbon border adjustment mechanism put a price on carbon for heavy industry. Canada, the UK and other countries have their own carbon pricing and incentives. Policy changes can make or break business models, so companies with economics that work without subsidies are more resilient.

Why climate tech is hard

• Capital intensity: building factories, plants and demonstration projects costs hundreds of millions of dollars before revenue.
• Long timelines: technologies like fusion or new materials can take a decade or more to commercialise.
• Commodity competition: clean products often compete with cheap incumbents, such as natural gas or conventional cement, on price.
• Policy dependence: subsidies and regulations can change with elections.
• "Valley of death": first-of-a-kind projects are hard to finance because they are too risky for banks and too large for venture funds.

Questions for evaluating climate tech companies

• Does the technology work at commercial scale, or only in pilots?
• Are there binding customer contracts, such as power purchase or offtake agreements?
• Do the economics work without subsidies?
• How will first-of-a-kind projects be financed?
• What is the measurable emissions impact?

What to watch

Watch fusion milestones such as SPARC's first plasma and Helion's Polaris results, data centre power deals, battery recycling economics, policy changes in the US and Europe, and climate company IPOs following Fervo's listing. Our list of unicorn companies shows how climate companies compare with other sectors.

Geothermal, nuclear and other firm clean power

Solar and wind are now the cheapest sources of new electricity in many places, but they don't produce power around the clock. Data centres, factories and grids also need "firm" clean power that runs whenever needed. That has revived interest in technologies that were long overlooked. Next-generation geothermal, which uses drilling techniques from the oil and gas industry to reach hot rock almost anywhere, has attracted large contracts; Fervo Energy's 2026 IPO showed public market appetite for it. Small modular nuclear reactors, from companies such as Kairos Power, X-energy, TerraPower and Oklo, have signed agreements with technology companies, although none has yet operated commercially. Existing nuclear plants have also benefited, with operators restarting or extending reactors to supply data centres.

Carbon removal and carbon markets

Many climate scientists say that cutting emissions won't be enough; the world will also need to remove carbon dioxide from the atmosphere. Approaches range from direct air capture machines and enhanced rock weathering to biochar, ocean-based methods and permanent storage of captured carbon in concrete, as CarbonCure does. Large buyers such as Microsoft, Frontier (a coalition including Stripe, Google, Shopify and others) and airlines have signed contracts for carbon removal, creating early demand. The market remains small and prices are high, and verifying that removal is real and permanent is a constant challenge, but advance purchase commitments have helped startups finance first projects.

Electric transport and grids

Electric vehicles remain one of the biggest climate technologies by investment, although private EV startups faced a difficult period as competition intensified and some incentives were cut. Charging networks, battery supply chains and grid upgrades continue to attract capital. Grid technology, including software that manages distributed energy resources, transmission equipment and devices that increase the capacity of existing power lines, has become a priority because connection queues for new power projects stretch for years in many countries.

How investors evaluate climate companies

Climate investors increasingly assess companies on both financial returns and measurable climate impact. They examine the cost curve of the technology, whether it can compete without subsidies at scale, the quality and length of customer contracts, the availability of project finance, and the emissions avoided per dollar invested. Infrastructure funds and strategic corporate investors now play a larger role in later-stage rounds, bringing longer time horizons and expertise in building physical assets.