One nagging concern has plagued fusion power businesses for a long time: Will the technology work?
Since net-positive fusion power is no longer the stuff of science fiction, however, a new generation of businesses has been established based on more commonplace queries: Is it possible to build reactors for less money? What are some ways to simplify maintenance? The responses might make the difference between success and failure.
At least that’s what Francesco Volpe thinks they will be. For decades, Renaissance Fusion’s founder and CTO has been researching fusion. Over the years, he has been inspired by a number of projects that have led to a novel design for a fusion reactor that is catching the interest of investors.
Renaissance told TechCrunch exclusively that it had raised a €32 million Series A1. Lowercarbon Capital participated in the round, which was led by the Révolution Environnementale et Solidaire fund of Crédit Mutuel Impact. With those funds, the business intends to construct a demonstration that should demonstrate the fundamental elements of its innovative design.
Fusion with a twist
Fusion power offers to use a plentiful fuel source to produce enormous volumes of clean electricity. The two methods that the majority of fusion companies are investigating are magnetic confinement, in which big magnets corral plasma into long-burning fusion reactions, and inertial confinement, in which lasers compress fuel pellets to spark fusion pulses.
Stellarators, like the ones Volpe is creating, are more appropriate for the latter category. Their ostensibly arbitrary bulges and twists serve to stabilize the plasma by collaborating with its peculiarities rather than opposing them. The concept’s viability was demonstrated by a significant experiment conducted in Germany, although producing its complex magnets proved difficult.
Grenoble-centered The goal of the Renaissance was to make the stellarator simpler. Its strategy combines rather than reinvents, and it is not the only business that tries to do so; Thea Energy is another.
The reactor architecture of the company resembles a polygon of segmented tubes, each embellished with etchings that resemble topographic map lines. The lines, however, are not merely decorative; rather, they indicate the high-temperature super conducting (HTS) magnets that give the interior plasma its peculiar shapes.
“I wanted to make these as simple as possible,” Volpe told TechCrunch.
His graduate work with the experimental stellarator Wendelstein 7-AS served as the impetus for the initial simplification, the segmented tubes.
“You kind of recognize a pentagonal form when you look at that from the top,” he remarked. I thus reasoned that we ought to push this to its farthest. We should actually construct cylinders, not just approximate ones.
While cylinders are used in other reactor designs, they typically form plasma into doughnut shapes rather than the extreme curves that characterize stellarators. Volpe used the work of a Spanish colleague who 3D printed a structure to guide inexpensive, flexible cables into the shape of a stellarator to give his idea the twists it needed. Although the wires were much easier to construct than the intricate magnets used in most stellarators, the 3D printing component wasn’t quite as viable for commercialization.
Volpe made the concept more simpler. He flattened them instead of trying to duplicate the intricacy of the plasma in three-dimensional magnets. Wide sheets of HTS magnets will be applied to the tubes in Renaissance’s design. A laser will etch a series of thin, winding lines around the tube into that covering. These
The magnetic field will be stronger at locations with wider superconducting stripes. They will exert more force against the tube’s plasma. The plasma can bulge because the magnetic field is weaker where the material is thinner. Advanced computer models will be used to establish the precise geometry of the plasma.
Renaissance will fill the tubes with liquid lithium to shield them from neutrons that could shoot out of the fusion event. The business applies an electric current to the liquid metal, creating a magnetic field that will attract the liquid to the strong magnets on the exterior of the tubes, ensuring that the liquid flows against the wall and does not leak into the plasma. Small spheres of molten lead suspended in the liquid will absorb some of the neutron bombardment. By producing more fuel for the reactor and transmitting heat to power steam turbines, the liquid blanket will also perform three tasks.
Magnetic carpets
According to Volpe, Renaissance plans to start producing wide HTS “carpets” in the upcoming months. By the end of 2026, a demonstrator that combines liquid lithium walls with tubular HTS magnets should be available. Like other fusion businesses, Volpe anticipates that the company will be able to construct a full stellarator by the early 2030s.
Although each component seemed promising on its own, Volpe hopes the prototype will show that the idea is more comprehensive than the sum of its parts and could lead to a less expensive fusion reactor. “You make the connections. It’s what inspires people,” Volpe remarked.