Renaissance Fusion Brings Hope to the Nuclear Industry

Thanks to several game-changing innovations, the young start-up has strong ambitions to simplify and accelerate the deployment of this promising technology for the green transition.

Renaissance Fusion Brings Hope to the Nuclear Industry

One step forward, one step back. Advocates of nuclear fusion no longer know which foot to dance with. Last November, his enthusiasm was dampened by the announcement of a delay of at least five years in the construction of the Iter experimental reactor, an international project located in Cadarache, in Bouches-du-Rhône. A few weeks later, however, their smiles return when the public research center National Ignition Facility (NIF), located in the United States, manages for the first time to use fusion technology to produce more energy than injected the 192 laser beams into the plasma. where the reaction takes place. A great advance, but tempered by the greed of these lasers, which, in order to work, required almost a hundred times more electricity than was produced in the end.

Deputy Administrator for Defense Programs at the National Nuclear Security Administration, Dr. Marvin Adams holds a cylinder as he explains the advancement in fusion research during a press conference at Department of Energy and Defense headquarters on December 13, 2022 in Washington. Credit: Chip Somodevilla/Getty Images/AFP

It must be said that the hopes raised by nuclear fusion since the 1930’s are living up to the potential of this technology. It is based on a physical reaction similar to that of the sun or other stars, namely the fusion of light nuclei, usually deuterium and tritium, to create a heavier element. The process then releases energy. A different approach to the process that is at the heart of all current nuclear power plants, fission, which consists, on the contrary, of breaking large uranium nuclei to form smaller elements. Nuclear fusion thus promises to retain the advantages of fission – carbon-free, controllable, non-intermittent electricity – without retaining the main disadvantages: no risk of devastating chain reactions, no radioactive waste for hundreds of thousands of years, not to mention about the abundance in nature of one of the two necessary elements, deuterium.

But there is still much to be done. To force marriage between these molecules, they must bathe in a plasma heated to almost 150 million degrees – much hotter than the sun! – to ensure the continuity of the reaction. There are still many challengeslists Simon Belka, project manager at Renaissance Fusion, a French startup involved in building a fusion reactor. We have to find the right materials to withstand these very high temperatures, we have to reduce the size and price of reactors and, above all, we have to demonstrate that we can produce much more energy than we inject into the plasma to heat it up, including the installation operation. » For the time being, neither of the two major technologies today, the inertial confinement tested within the NIF or the magnetic confinement used by Iter, of the “tokamak” type, is capable of overcoming these challenges. In an attempt to address these, Renaissance Fusion embarked on a third path.

Stellarator vs Tokamak

Founded in 2019 in Grenoble, the start-up is based on the work of its founding president, Italian physicist Francesco Volpe. For twenty-five years he was able to try out various nuclear fusion devices and make his choice.says Simon Belka. The “stellarator” seemed to him the most suitable for the commercial production of fusion energy. »

Francesco Volpe, Founder, CEO and Technical Director of Renaissance Fusion, surrounded by Simon Belka (Project Manager, right) and Diego Cammarano (Director of Operations). Credit: Renaissance Fusion

Under this barbaric and somewhat futuristic name, this technology resembles in certain respects the tokamak-type magnetic confinement used by Iter. In both cases, the plasma is trapped within a magnetic field that insulates it from the reactor walls to protect them. The whole structure can be imagined as a big donut, lined with superconducting magnets to create the magnetic field and circulate the plasma in your heart.

simulation of the structure of the future reactor. Credit: Renaissance Fusion

But the tokamak presents several difficulties: “The tokamak is inherently pulsed: its energy output is intermittent. Produces fusion for a few minutesexplains Simon Belka. In addition, the current circulating inside the plasma generates instability and ruptures, electron beams can appear, reach and damage the walls of the reactor. »

So many problems that the stellarator principle can solve. By using complex shaped magnets, the plasma can theoretically circulate continuously and the reaction not stop. A major advance over laser or tokamak technologies. But, until now and as it had been tested for example in Germany, the stellarator was, because of its peculiar magnets, very difficult to design and build.

smaller, cheaper

Renaissance Fusion has developed two technologies, protected by a battery of patents, to overcome these obstacles. The first is to engrave complexly shaped magnets using a laser, directly onto the reactor housing. Thus, there is no need to give the structure a complicated shape and the presence of these magnets ensures a continuous process.

The second is based on the design of liquid metal walls inside the reactor, circulating thanks to a magnetic field. “This gives us several advantages, says Simon Belka. The liquid lithium protects the solid walls of the reactor, absorbs neutrons much better, conducts the heat produced by the fusion to the secondary circuit and the turbine producing electricity and, finally, when reacting with the plasma, it creates the tritium necessary for operation. »

Work session at Renaissance Fusion. Credit: Renaissance Fusion

Furthermore, by using a new generation of superconducting materials, Renaissance Fusion allows the construction of fusion reactors four to five times smaller than those currently planned and therefore less expensive. Finally, the continuity of the process ensured by the complex magnets allows eliminating instabilities in the reaction and sending most of the electricity to the network instead of being reused to maintain the fusion. As a result, the start-up announces the production of electricity at an estimated cost between 40 euros and 80 euros per MWh, that is, between solar and new generation fission nuclear. Now it remains to put theory into practice.

A first reactor in ten years

By 2024, Renaissance Fusion intends to finalize the engineering of its two main technologies, the recording of superconducting magnets and its liquid metal wall, in order to be able to launch manufacturing and, above all, its commercialization in sectors where they present a real added value, such as medical imaging, energy storage or particle accelerators. For this first step, we raised several million euros from private investors, which allows us to finance ourselves in large part », informs Simon Belka, without revealing the value of the operation. The company’s team should therefore grow, from 23 employees to around sixty next year.

Once these proofs of concept are completed and the marketing launched, the start-up will work on building a first experimental reactor to demonstrate, in particular, that it is capable of producing more energy than it needs. Finally, in the early 2030s, it should inaugurate its first reactor with a capacity of 1 GW capable of injecting electricity into the grid.

“Compared to large international public projects, start-ups offer an interesting alternative: we bring new ideas, we take more risks to create disruptions and we are less dependent on public funding. The two are complementary, I am convinced that the advent of the merger will go through public-private partnerships », assures Simon Belka. A new perspective to hope that capturing the sun in a box is not just an Icarus dream.

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