Renaissance Fusion: French-style nuclear fusion

Renaissance fusion is a Grenoble-based startup founded in 2020, developing a Stellarator-type nuclear fusion technology.

The principle of nuclear fusion

Nuclear fusion is a natural process that occurs when two light atomic nuclei, such as deuterium and tritium, combine to form a heavier nucleus, such as helium. During this reaction, a large amount of energy is released in the form of electromagnetic radiation and high-energy particles. This process is responsible for stellar energy production, including that of the Sun, where fusion of the hydrogen nucleus produces helium and releases energy in the form of light and heat. Unlike nuclear fission, it does not produce long-lived radioactive waste. Only the core of the fusion reactor is contaminated by the process.

Nevertheless, nuclear fusion is still far from being mastered. The conditions required to initiate and sustain a fusion reaction, such as extremely high temperatures and pressures, are difficult to achieve and maintain on Earth. Many challenges remain in developing a commercially viable fusion technology, including the design of materials capable of withstanding these extreme conditions, and the development of methods to confine and control the fusion plasma.

The Renaissance Fusion stellarator

There are several nuclear fusion technologies: magnetic or inertial confinement, then, among the magnetic confinement technologies, the tokamak, the stellarator and others. Renaissance Fusion is developing a Stellarator. This type of reactor was developed in the 1950s by the American physicist Lyman Spitzer. It features a complex configuration of external magnetic coils that generate a torsionally-shaped magnetic field. This configuration confines the plasma in a helical shape, helping to stabilize the plasma and reduce energy losses.

Unlike tokamaks, stellarators do not require an electric current to flow through the plasma to maintain the magnetic field. This eliminates the problem of disruptions, which are sudden instabilities in the plasma that can cause loss of confinement and damage to the device. As a result, stellarators are considered to have steady-state operating potential, which is important for a fusion power plant. That’s why Renaissance Fusion has chosen this technology.

They are currently offering two innovations:

  • A technology to facilitate reactor design by laser-engraving the complex shapes of the magnets.
  • Liquid metal (lithium?) walls inside the reactor, circulating thanks to a magnetic field.

History and progress of Renaissance Fusion

Renaissance Fusion was founded by Francesco Volpe and Martin Kupp in 2020 and is based in Grenoble.

In June 2022, the company announced that it had raised €15 million from Lowercarbon Capital, Norrsken>C, positron ventures, Excellis, Unruly capital, HCVC and Exor.