With new $100 million raise, Princeton University’s Thea Energy is now top-funded merger startup

Thea Energy has raised a $100 million Series B round led by US Innovative Technology Fund, the merger startup told TechCrunch. This amount places the company among the best-funded fusion startups, giving it a better chance of creating a commercial reactor.

The new funding will help Thea scale up manufacturing of its uniquely designed micromagnets and begin building Eos, a “power station-related” demonstration device, starting next year. Thea previously closed a $20 million Series A in early 2024. The new round brings total private investment to $130 million, the startup told TechCrunch.

Magnets are at the heart of many fusion power plant designs, keeping the extremely hot material called plasma compressed and burning enough to fuse atoms, which in turn release heat and energy. But Theia magnets are different: Each rectangular magnet can be adjusted to create the shape of the reactor’s overall magnetic field. These are like the pixels in a computer screen, which collectively follow software instructions to create the text and images the screen displays.

For Thea, this flexibility will be important. The type of reactor you design is known as a stellarator. Stars are able to maintain plasma in very stable configurations, but to do so, they must twist and bend to accommodate the plasma. This is in contrast to the tokamak, another pioneering magnetic design, which uses more brute force to keep the plasma confined.

But the irregular shape of the star increases the complexity and cost of manufacturing magnets. Thea is betting that by covering his reactor core with dozens of ordinary magnets, he can use software to control smaller, rotatable magnets and create a star-shaped magnetic field within a much simpler physical structure.

The program should also assist in assembling the reactor. Thea had intentionally installed test magnets out of alignment, but the software was able to compensate.

Thea hopes to complete its experimental Eos reactor in 2030 with a commercial version, known as Helios, that will become operational in 2034. That timing puts it in line with competitors like Commonwealth Fusion Systems, which has said it hopes to have its Arc reactor in Virginia operational in the early 2030s.

If Theia’s pixel-inspired magnets are successful, the company could have a manufacturing advantage. The startup has built dozens of iterations of its large-scale magnets at its lab in Jersey City. Meanwhile, other nuclear fusion startups seeking magnetic confinement have had to build massive assembly halls to manufacture reactor-sized magnets.

However, small magnets don’t do all the lifting. Theia uses 12 magnets of four different shapes outside of flat coils to handle most of the plasma confinement. Smaller magnets of over 300 adjust the plasma. Relying on larger magnets erodes the company’s manufacturing advantage somewhat.

However, any simplification of the nuclear fusion reactor – which is already one of the most complex devices ever built by humans – will help pave the way for nuclear fusion energy. An extra $100 million doesn’t hurt either.

Other investors who participated in the round include: General Innovation Capital Partners, Linse Capital, Calm Ventures, Climate Capital, Divergent Capital, Emerald Technology Ventures, Gaingels, Idemitsu Kosan, Overlay Capital, Timescale Ventures, and What If Ventures.

Update: Early Theia designs called for the use of 12 surrounding magnets. It has not been added to later versions.