Thea Energy raises $100M Series B to scale stellarator fusion plants
Thea Energy , a New Jersey-based fusion startup, has closed an oversubscribed $100M Series B round to advance its stellarator technology toward commercial deployment. Thomas Tull's US Innovative Technology Fund (USIT) led the raise, with participation from General Innovation Capital Partners, Linse Capital, and a broad syndicate including Calm Ventures, Climate Capital, Idemitsu Kosan, and others. Existing backers such as Lowercarbon Capital, Hitachi Ventures, and Prelude Ventures also joined.
The funds will expand Thea Energy's magnet manufacturing capacity — including a second facility in Northern New Jersey — and support construction of "Eos," a large-scale integrated stellarator designed to produce steady-state fusion. The company plans to select a site for Eos later this year and double its team.
Surging demand for baseload power, driven by AI infrastructure and broader re-industrialisation, has made fusion a strategic priority. The US Department of Energy recently certified Thea Energy's power plant preconceptual design milestone, giving the company a credibility boost at a moment when governments and investors are racing to back viable fusion approaches.
"We built Thea Energy to take fusion out of the lab and onto the grid," said co-founder and chief executive officer Brian Berzin. "Our architecture is simpler to manufacture, faster to construct, and more tolerant of real-world conditions compared to all other approaches."
The company aims to begin construction of its first "Helios" power plant before the end of the decade.
Fusion energy has attracted billions in investment but remains unproven at commercial scale. Stellarators — which use complex 3D magnetic fields to confine plasma — have historically been difficult and expensive to build. Thea Energy claims it has solved this by shifting complexity from precision mechanical fabrication to software-defined controls, but that thesis is yet to be validated at power-plant scale.
Timeline risk looms large. Fusion startups routinely face delays, and moving from an integrated demonstration system to a grid-connected power plant involves enormous engineering, regulatory, and financial hurdles.
Thea Energy's jump to "breakout" growth stage, according to Dealroom, underscores how quickly stellarator technology has moved from academic curiosity to investable thesis. The breadth of the syndicate — spanning Thomas Tull's USIT, climate-focused funds like Lowercarbon Capital and Prelude Ventures, and Japanese industrial giant Idemitsu Kosan — signals that fusion capital is diversifying beyond tokamaks and toward architectures that promise simpler manufacturing and faster construction timelines.
Read more: Business Insider
