Fusion startup Thea Energy secures $100M Series B funding

Thea Energy has raised an oversubscribed $100 million Series B funding round to scale its magnet manufacturing and begin construction on its Eos demonstration reactor. The investment round was led by the U.S. Innovative Technology Fund. The new capital will help the fusion startup expand manufacturing for its magnets and begin construction of its Eos demonstration device. The funding places the company among the better-funded fusion startups as it attempts to build a commercial-scale reactor.

The company is developing a stellarator, which is a type of magnetic confinement fusion reactor capable of keeping plasma in stable configurations. This design contrasts with tokamaks—an alternative leading magnetic fusion reactor design—which use more brute force to keep plasma confined. While stellarators traditionally require complex, twisted physical structures that drive up manufacturing costs, Thea Energy is using software to control smaller, tunable magnets to create the necessary magnetic field within a simpler physical structure. The design utilizes 12 magnets of four different shapes outside the planar coils to handle the bulk of the plasma confinement, alongside 300-plus smaller magnets to fine-tune the plasma. The startup has built dozens of iterations of these magnets in its laboratory in Jersey City. If this approach succeeds, it could provide a manufacturing advantage over competitors like Commonwealth Fusion Systems, which have had to build massive assembly halls to construct reactor-scale magnets.

The oversubscribed Series B round follows a $20 million Series A closed in early 2024, bringing the startup’s total private investment to $130 million. Thea Energy hopes to complete its Eos demonstration reactor in 2030. Following the demonstration phase, the company hopes to bring its Helios commercial version online in 2034. This timeline brings the startup in line with competitors like Commonwealth Fusion Systems, which hopes to bring its Arc reactor online in Virginia in the early 2030s.

A broad syndicate of venture and strategic investors joined the round. Other investors who participated in the Series B funding include:

• General Innovation Capital Partners
• Linse Capital
• Calm Ventures
• Climate Capital
• Divergent Capital
• Emerald Technology Ventures
• Gaingels
• Idemitsu Kosan
• Overlay Capital
• Timescale Ventures
• What If Ventures

Why it matters

The $100 million Series B funding places Thea Energy among the better-funded fusion startups, supporting the construction of its Eos demonstration device and the expansion of its magnet manufacturing.