Historic breakthrough in nuclear fusion, the energy of the future

American scientists announced on Tuesday that they have achieved a historic breakthrough in nuclear fusion: for the first time, they have been able to produce more energy in the laboratory than they need for the reaction.

For many, nuclear fusion is the energy of the future. It has several advantages: it does not emit any CO2, it produces less radioactive waste than nuclear energy to date and it does not pose any risk of accidents.

Fusion differs from nuclear fission, the technique currently used in nuclear power plants that breaks the bonds of heavy atomic nuclei to release energy.

Fusion is the opposite process: two light nuclei (for example hydrogen) fuse to form a heavy nucleus (helium), releasing energy.

It is the process that takes place in stars such as the sun.

“Controlling the power supply of the stars is humanity’s greatest technological challenge,” physicist Arthur Turrell, author of The Star Builders, wrote on Twitter.

Fusion is only possible by heating matter to extremely high temperatures, about 150 million degrees Celsius.

METHODS Erik Lefebvre, project manager of the French Atomic Energy Commission (CEA), told AFP: “Mechanisms must be found to isolate this extremely hot substance from anything that could cool it.”

The first method is magnetic confinement fusion. Light hydrogen atoms (deuterium and tritium) are heated in a huge reactor. Matter is then in a plasma state, a gas with a very low density. It is controlled by a magnetic field.

This is the method used for the international project ITER currently under construction in France and the JET (Common European Torus) near Oxford.

A second method is to send very high energy lasers into a thimble-sized cylinder of hydrogen. This is the technique used by the US National Ignition Facility (NIF). The latter was used for the final experiment.

Until now, the primary goal of laser labs has been to demonstrate the physical principle, while the first method attempts to reproduce a configuration close to a future fusion reactor.

Assuming these projects require another 20 or 30 years of work, Erik Lefebvre warns “there is still a long way to go” towards “an industrial-scale demonstration that is economically viable”.

There were probably “decades” (but less than five) on Tuesday, said Kim Budil, director of the Lawrence Livermore National Laboratory, to which the US NIF is affiliated.

Now that the net energy gain has been achieved with lasers, “we need to figure out how to simplify this,” he added.

The method requires several technological improvements: because it is necessary to be able to repeat the experiment many times per minute and to increase the power.

Unlike nuclear fission, nuclear fusion poses no risk of nuclear accidents. Lefebvre explains that in the event of a system failure, the response stops completely.

Smelting also produces less radioactive waste than current power stations. And it produces no greenhouse gases.

“This is a completely low-carbon energy source that produces very little waste and is naturally very safe,” summarizes Lefebvre, as it “will be a solution to global energy problems for the future.”

Due to its state of development, it does not offer a direct solution to the climate crisis, making the transition from fossil fuels inevitable.

Another advantage is that it uses elements such as deuteron and lithium, which are abundant in nature and can be used to produce almost unlimited energy.

The idea to use this technique came after the laser was proposed in 1960 by John Nichols, a physicist from California headquarters, to use these beams to cause controlled nuclear fusion in a laboratory.

“CO2-free environment”

Physicist Denise Hinkel started working 30 years ago at Lawrence Livermore National Laboratory (California, USA), where she was fascinated from the start by a nuclear fusion project that “will not only be a scientific challenge, but will have a huge impact on humanity .” . .

Hinkel is part of the team of scientists that achieved nuclear fusion for the first time with a net energy gain, i.e. producing more energy than is used in the process.

The physicist stated that fusion power “will make a big contribution to the fight against climate change,” said the physicist, “It would be a big step towards a low-carbon environment if you didn’t have to burn oil.” It also emphasizes that it will add another source of energy, “because at some point our natural resources will run out.” Hinkel explains that “fusion power is the process that powers the sun.” In this way they simulated stellar conditions and managed to combine them with a net energy gain.