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With $16.4 million Europe’s Renaissance Fusion is “building a super-star on Earth”

The sun from outer space
Image credit: NASA

In 2019 Grenoble, France-based Renaissance Fusion became the first magnetic confinement fusion start-up in continental Europe. Now, after closing a $16.4 million seed round, the startup hopes to achieve a crucial milestone this year: prove its flowing liquid walls, the heart of its stellarator fusion reactor.

Renaissance describes the stellarator as a “super-star on Earth.” Like tokamaks, the leading candidate for plausible fusion, the stellarator is a donut-shaped device that magnetically levitates hot ionized gasses called plasmas and heats them to temperatures hotter than the Sun.

Tokamaks are largely seen as the key to a fossil fuel-free utopia, and according to the international fusion experiment, ITER, their tokamak will be the largest, most powerful fusion device in the world.

But according to the U.S. Department of Energy, there is one problem that even ITER hasn’t solved: how can it keep the core of a plasma hot enough that fusion can occur while preventing the tokamak walls from melting from that heat?

There are several efforts currently in the works to clear fusion's hurdles, such as FootPrint Coalition-based Commonwealth Fusion Systems with its superconducting magnet.

Renaissance’s efforts are unique because they want to use liquid lithium to create thick walls that will separate this plasma from the outside world. In theory, this will keep the donut’s walls from melting.

According to the startup, this approach bests tokamaks because the stellarator is cheaper to operate and is more efficient because it does not need a current in the plasma, thus it naturally evades any current-related instabilities found in tokamaks.

Another other fusion method utilizes a laser to compress a capsule to very high pressures. Even though laser methods don’t run into the heat problem, Renaissance says the stellarator is better because it has a higher efficiency, delivering a multitude more of energy because unlike laser machines it can stay “on” all the time.

Renaissance isn’t oblivious to the challenges ahead of their novel fusion reactor, from modeling to manufacturing. Still, by the not-so-distant 2030s, the startup expects to be able to ship a small nuclear fusion reactor with a 1-gigawatt capacity.

Unlike other fusion ventures, the company doesn’t plan to operate out of a power plant directly. As reported in TechCrunch, instead the company will sell its reactors to plant constructors and operators.

Lowercarbon Capital and several European investors such as HCVC, Positron Ventures, and Norrsken led the round. Unruly Capital led the company’s pre-seed round.

With the money, Renaissance hopes to triple the size of its team from 23 employees to 60 people by the end of 2023, and by 2024, Renaissance intends to finalize the engineering of the technology.

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