Grenoble and Houston-based French startup Renaissance Fusion has raised $16.4 million in a seed round led by Lowercarbon Capital. Founded in 2019 by Francesco Volpe and Martin Kupp, Renaissance Fusion is working on the development of a stellarator reactor. The company plans to be able to deliver a small fusion reactor with a capacity of 1 GWe in the 2030s. It does not plan to operate the plants directly, but will sell its reactors to plant builders and operators.
Several European investors also participated in the round, including HCVC, Positron Ventures and Norssken. Unruly Capital led the company’s pre-seed round. With the new funding, Renaissance Fusion plans to triple the size of its team to 60 people by the end of 2023.
Renaissance Fusion offers a unique set of technologies that it plans to use in its stellarator-type fusion reactor. These include liquid metal that adheres to the inner walls of the reaction chamber, insulating the walls from extreme heat and radioactivity and reducing maintenance costs. The company also develops high-temperature superconducting coils. They create strong magnetic fields, allowing a smaller reactor to achieve the same performance as a larger reactor.
A new manufacturing process using high-temperature superconducting magnets (HTS) allows the reactor to be divided into individual modules. “We have a pretty unique technology,” Renaissance Fusion told Techcrunch. Instead of designing complex three-dimensional coils to create the magnetic field, the company simplifies the process by drawing tracks on the cylinder using a laser.
After the calculation, based on the required magnetic field, the team can determine the required shape of the coils. The cylinder rotates on an axis while the device moves left and right to laser engrave tracks on the surface of the cylinder. The cylinder blocks are then combined to form a reactor.
To combat the neutrons released by the fusion reaction inside the cylinder, liquid lithium is what lines the walls containing the plasma.
Volpe explained: “We inject a layer of liquid metal. It flows around the inside of the cylinder and is then drawn out at the bottom. It is thick enough to absorb most neutrons.
The design of liquid metal walls inside the reactor offers several advantages, according to project manager Simon Belka. “Liquid lithium protects the solid walls of the reactor, absorbs neutrons much better, conducts the heat from fusion to the secondary circuit and the turbine that produces electricity, and finally reacts with the plasma to produce the tritium necessary for operation. “
Volpe said Renaissance Fusion is pioneering the use of liquid metal. “We are the only ones in commercial magnetic fusion where the liquid lithium is facing the plasma.” Currently, the company can create liquid lithium-based walls that are 1 cm thick. It will require considerable development before it can be used in fusion, which would require a thickness of 30-40 cm.
The company is already considering commercial applications for its technology, which could be released before the 2030s. Volpe believes the coil-patterning technology could be used in MRI and energy storage — “anytime you need a strong magnetic field, high volume, and high precision,” he said.
By 2024, Renaissance Fusion plans to complete the development of two of its technologies. Once these proofs of concept are complete and marketing begins, the company will work on building the first experimental reactor specifically to demonstrate that it can produce more energy than it needs. Finally, in the early 2030s, it should unveil its first 1 GWe reactor capable of feeding electricity into the grid. “Compared to large international public projects, startups offer an interesting alternative: we bring new ideas, take more risks to create disruption and are less dependent on public funding,” said Belka.
Image: Renaissnace Fusion’s leadership team, including founder Francesco Volpe (center) (courtesy of Renaissance Fusion)