To build a fusion power plant, engineers are forced to make some difficult choices. Do they go with the simplest design and then, while in operation, force the creature to behave so that it doesn’t go out? Or do they choose a complex design that is difficult to build but leads to a happier creature?
Or what if there was a way to do both?
Thea Energy hopes that “both” is the correct answer. The startup is betting that software can replace manufacturing precision in its quest to deliver reliable, cheap fusion power. It recently raised a $20 million Series A, according to TechCrunch exclusively. Prelude Ventures led the round with participation from 11.2 Capital, Anglo American, Hitachi Ventures, Lowercarbon Capital, Mercator Partners, Orion Industrial Ventures and Starlight Ventures.
There are two main approaches to fusion power: inertial confinement and magnetic confinement. The first made headlines in late 2022 for proving that net positive fusion power isn’t just science fiction by using massive lasers to vaporize a globule of fusion fuel.
Many startups, however, use some variation of the latter. In magnetic confinement, the burning plasma is contained by strong magnetic fields produced by high-temperature superconductors. These fields squash the plasma into one of several shapes: In tokamaks, the donut-shaped designs that many large reactor projects use, these magnets must be made with incredible precision to be able to contain plasma and keep it at the right temperature .
In stellarators, the magnets have to be even more precise, but several startups favor the design because it’s easier to achieve stable plasma in them. Tokamaks are often compared to classic, elevated doughnuts. I like to think of stellarators like old-fashioned doughnuts: irregular in shape, but still a donut at heart.
The entire asteroid twists and turns according to the plasma’s requirements, which are calculated in advance. The shape comes from their deliberately distorted magnets, and making each magnet right requires a lot of engineering and manufacturing know-how, which add to the cost.
The Thea Energy team wanted to build a stellarator, but didn’t want to go through all that hassle. Instead, they use an approach developed at Princeton’s Plasma Physics Laboratory that lines a donut-shaped reactor with an array of high-temperature superconducting magnets each controlled by software. By extending and retracting the fields of different magnets, the array can make the creature behave as if it were inside a more complex constellation.
None of this is simple, of course. Nothing in fusion power is simple. “We haven’t eliminated complexity. we have not eliminated precision,” Brian Berzin, co-founder and CEO of Thea Energy, told TechCrunch. “But what we did is we removed as much of the material as possible and pushed it into the control systems.”
Berzin compares the flat star coil design to a computer screen. Each magnet is like a pixel that can be controlled individually. Because they create a star shape, with its inherent stability, the computers that control them won’t need to be anything exotic. “We’re talking about things that you don’t even need clusters of servers to run,” he said. “There is no near-real-time computation necessary.”
Thea believes her approach is better at containing the creature than competing plans. “An order of magnitude better containment,” Berzin said. “You can make a more accurate asteroid than you could have with modular crazy coils.”
The modular approach should also speed up system development. The company currently manufactures full-scale magnets inside its Jersey City lab. By comparison, the magnets that will form ITER’s 64-foot tokamak are assembled in a large warehouse in the French countryside. Thea’s tiny magnets can be tested in the same lab both individually and in small arrays that mimic parts of the final design.
“We can repeat multiple generations in a year without spending too much money on a single piece of hardware,” Berzin said.
Thea plans to build a pilot-scale reactor later this decade and a larger-scale 350-megawatt demonstration unit in the 2030s. By the time its commercial offering is connected to the grid, it hopes to generate power at $50 per megawatt hour. That’s right at the low end of where solar and battery power is today, according to Lazard. It is marginally more expensive than a combined cycle gas power plant today and slightly less than coal. In other words, if Thea hits her target, she could have a competitive bid on her hands.
Like all fusion power startups, the same caveats apply: The technology is incredibly difficult to master, so difficult that no one has yet done it on a commercial scale. Once they do, it will be a matter of containing costs so reactors can compete with renewables and batteries, both of which continue to fall in price. There are a few ways to do this, but Thea’s approach is clever enough that it might work. Software has managed to take over many other industries. Why not fusion?
