Proxima Fusion raises €411M as Google, RWE back stellarator tech

Google and a major German utility are betting on an unproven reactor design to deliver Europe's first commercial fusion power plant.

Proxima Fusion raised €411 million from Google and RWE at a €2.4 billion valuation, betting stellarator technology can deliver Europe's first commercial fusion power plant by the end of the decade.

"Europe is racing with the United States and China to get to the first fusion power plant," Francesco Sciortino, cofounder and chief executive officer of Proxima Fusion, said in a statement.

The round was led by XTX Ventures and East X Ventures, with RWE investing €25 million and Google participating as a strategic investor. Other backers included Plural, UVC Partners, Balderton and Cherry Ventures. The Munich-based startup plans to build its fusion demonstrator by the early 2030s, followed by a commercial plant later that decade on the site of a former nuclear fission plant in Gundremmingen, Bavaria, under an agreement with RWE.

The investment underscores growing corporate appetite for fusion energy, which promises abundant carbon-free power without the radioactive waste of fission. But the technology remains unproven at commercial scale. US rivals have raised far more: Commonwealth Fusion Systems has collected $2.9 billion total, including $863 million in August, while Sam Altman-backed Helion Energy has raised $1.5 billion. Google, which also invested in CFS and signed an offtake agreement in June 2025, acknowledged that commercializing fusion is "immensely challenging, and success is not guaranteed."

Stellarators vs. Tokamaks — Why the Design Matters

Proxima is developing stellarator technology, a magnetic confinement approach that differs from the more common tokamak design used by competitors like Commonwealth Fusion Systems and Helion. Stellarators use twisted magnetic coils to contain plasma without the need for a continuous electric current, offering inherently stable operation. The trade-off has historically been extreme engineering complexity — early stellarators required magnets twisted into shapes that were nearly impossible to manufacture at scale.

Proxima says advances in high-temperature superconducting (HTS) cables and magnets, combined with computational optimization, have made stellarators commercially viable. The company will use the new funding to expand HTS cable and magnet production capacity and develop the engineering and manufacturing systems required for its reactor design.

Europe's Fusion Bet vs. US Firepower

Proxima's €411 million round makes it the best-funded fusion startup in Europe by a wide margin, but it still trails US competitors. Commonwealth Fusion Systems, a Massachusetts-based tokamak developer, has raised $2.9 billion to date. Helion Energy, backed by OpenAI's Sam Altman, raised $465 million last month, bringing its total to $1.5 billion. Both US companies target commercial operation before 2035.

The disparity reflects different capital environments. US fusion startups have benefited from deeper venture pools and Department of Energy programs, while European startups have relied more on corporate strategic investors and utility partnerships. RWE's involvement — including a specific site for Proxima's first plant — gives the German startup a concrete path to deployment that few fusion companies anywhere can claim.

For investors tracking the energy transition, the Proxima round signals that fusion is moving from theoretical physics to industrial engineering. The €2.4 billion valuation implies early backers see a path to a commercially viable power plant within a decade. But with no fusion plant having ever generated grid-connected electricity, the gap between valuation and revenue remains wide. RWE's commitment of a former nuclear site and Google's repeat fusion investments suggest corporate off-takers are willing to place long-dated bets — even if the technology's timeline remains uncertain.

This article is for informational purposes only and does not constitute investment advice.