Climate venture capital investment made a dramatic turnaround in 2025, rising to $40.5bn, up 8% year-on-year, as the energy system began to absorb a step-change in demand from AI, data centers, and electrification, according to a new report by Sightline Climate. Investment had fallen in both 2023 and 2024.

Driving this climate tech investment growth is a structural shift away from emissions reduction and toward meeting rising energy demand. The rapid buildout of AI infrastructure and data centers is accelerating the need for power, including new clean firm capacity, grid flexibility, and backup power solutions. Technologies are expected to provide resiliency, speed to power, or lower costs, with lower emissions as a bonus, and those that fit the bill are drawing bigger checks than ever.

Overall, climate tech deal counts dropped by 14%, hitting a four-year low, while average deal sizes rose to levels not seen since 2020, as capital concentrated into fewer, larger, later-stage bets. Half of the top ten deals in 2025 were at or over $1bn, significantly surpassing average mega-deal sizes from 2024. Six of these deals were in the energy sector, while two were mega rounds for data center developers.

The built environment sector jumped 23% in 2025, largely driven by low-carbon data center investment, which made up 78% of the vertical’s funding. The energy sector also experienced a 31% increase in funding thanks to large nuclear and grid deals. Together, energy and built environment were responsible for the majority of investment growth in 2025, making up for weakness across other climate tech areas.

Investment peaked at $13.5bn in Q3, the strongest quarterly investment performance since Q3 2023. But this doesn’t look like a return to boom times. Investors doubled down on mega deals for popular bets, while the majority of the market struggled to find funding.

Hard-to-abate tech lost momentum amid climate policy headwinds. Sectors reliant on decarbonization targets and policy fell out of favor, with carbon funding declining 24% and industrial decarbonization funding dropping slightly by 3%.

A shift away from climate tech in the US could make Europe the new founder destination of choice. For the moment, the US’ deep capital stack is keeping existing startups in the States, but the next few years could see a wave of founders setting up in Europe to take advantage of steady government funding and a greater willingness to pay for emissions reduction technologies if carbon pricing signals remain stable.

However, European venture capital investment fell by 13% in 2025, to $10.1bn, the lowest level since 2020. While policy uncertainty hasn’t hit the region as hard as the US, there has been a noticeable pullback from the most aggressive climate policy along with some high-profile bankruptcies like Northvolt, seemingly making investors hesitant to back startups in the hard-to-abate sectors it previously championed.

Kim Zou, Co-founder and CEO of Sightline Climate, said: “Just like the wider market right now, energy systems, climate tech, and AI are now inextricably linked. Data centers are driving the energy demand that has caused a boom in clean firm power and gridtech investment. And decarbonization is no longer the primary motivation, it’s all about energy supply and security.

“This marks a new phase for climate tech. It’s growing up and hitting the tumultuous teenage years. Consolidation is continuing, with acquisitions staying high, but investment has seen an unexpected rebound, thanks to several billion-dollar deals in energy and data centers. The market is split: star companies in booming sectors are raising larger rounds than ever before, while those in sectors with declining policy support and big green premiums are struggling to find new funding.

“2025 was the year of the shift, 2026 will be all about speed and scale. As capital allocators like hyperscalers, utilities, and infra investors figure out how to bring online tens of gigawatts of new data center capacity, firm power will be at an even bigger premium, as will the companies with the tech to provide it.”

For more  information: https://www.sightlineclimate.com/

The report: https://www.sightlineclimate.com/request-report?report-id=2025_investment_report

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