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The United States is expected to announce on Tuesday that it has for the first time obtained a “net energy gain” during a nuclear fusion experiment. An important step to demonstrate the viability of this technology which, for its promoters, would be the “holy grail” of renewable energies.
Has an important step towards an infinite, non-polluting and inexpensive source of energy just been taken? The United States is preparing to announce, Tuesday, December 13, having obtained a “net energy gain” during a nuclear fusion experiment at the Lawrence Livermore National Laboratory in California (LLNL), said the Financial Times Sunday, December 11.
A world first confirmed by the Washington Post, which specifies that the Biden administration intends to insist on the importance of this progress. This would reinforce the White House’s choice to have made nuclear fusion a priority of the climate plan promulgated by Joe Biden in August 2022, specifies the reference daily.
“This is a feat that scientifically confirms for the first time the validity of the concept of nuclear fusion,” says Ambrogio Fasoli, physicist and director of the Swiss Plasma Center at the Ecole Polytechnique in Lausanne, Switzerland. This technology consists of reproducing on Earth the physical reaction that leads to the generation of light and energy on the Sun by propelling two atoms at very high speed, hoping that they will merge.
The “net energy gain” is a crucial step in the path traveled for more than seventy years by the promoters of nuclear fusion, who hope to see it become the “Holy Grail of renewable energies”, underlined in April Don Beyer, Democratic representative in Congress during the presentation of the new American plan to develop this sector.
This breakthrough made it possible to demonstrate that there was “more energy released during nuclear fusion than that used by the lasers necessary to provoke the reaction”, explains Sibylle Günter, scientific director of the Max-Planck Institute of Plasma Physics, one of the most important German research centers in the field of nuclear fusion.
In this case, the physicists of the LLNL would have managed to generate 2.5 megajoules of energy while the lasers projected only 2.1 megajoules to provoke the physical reaction, specifies the Financial Times.
Bombardment by lasers
This success, described as a “historic moment” by the British physicist Arthur Turrell, was long awaited. Easy to demonstrate in theory, the “net energy gain” was much more difficult to achieve in practice, underlines the Financial Times. The problem comes essentially “from the particles of the atomic nuclei which do not want to get closer unless they are heated to nearly 150 million degrees Celsius”, underlines the physicist Ambrogio Fasoli.
To achieve such temperatures, it is necessary to use means which are themselves very energy-intensive. The California lab behind the breakthrough expected to be announced on Tuesday used inertial confinement nuclear fusion, one of two main methods to achieve this result (the other, called magnetic confinement fusion, is particularly at the heart of the European Iter project, currently being developed in Cadarache, in the south of France).
The process used by the LLNL consists of bombarding a very small fuel capsule – about a millimeter in size – with laser beams which will heat it and condense it strongly until “the outer ‘shell’ of the capsule explodes and releases the energy”, summarizes Alf-Köhn Seeman, specialist in nuclear fusion at the University of Stuttgart. Tuesday’s official announcement should help to better understand how American scientists managed to break the deadlock of energy-intensive lasers to achieve this historic “net energy gain”.
If “this feat is remarkable from a scientific point of view, it does not bring us much closer to a commercial development of nuclear fusion”, however believes Roger Jaspers, physicist at the Eindhoven University of Technology, associated with several magnetic confinement nuclear fusion projects.
Still a long way before commercial nuclear fusion
First, because you must already know what gain we are talking about. “We don’t know, for example, how much electricity was used to charge the lasers,” says Roger Jaspers. In other words, if electricity consumption is taken into account, there may not even have been a “net gain” in energy.
Second, to be commercially viable, nuclear fusion must be able to continuously supply electricity to the grid. This is far from the case with the experiment carried out at the Lawrence Livermore laboratory. “Currently, it takes several days to adjust all the settings to achieve capsule fusion. A plant should achieve this about ten times per second. [pour générer de l’électricité en continu]“, underlines Sibylle Günter, the scientific director of the Max-Planck Institute for Plasma Physics.
Proponents of nuclear fusion by magnetic confinement – a method in which huge magnets are used to hold the fuel at a necessary heat – believe their path overcomes some of the problems inherent in the process used in California. But for the time being, they have not yet reached the famous “net energy gain”… Even if “it is inevitable in the years to come”, estimates Alf-Köhn Seeman, from the University of Stuttgart.
If the success of the Lawrence Livermore laboratory is confirmed on Tuesday, the dream of an inexhaustible source of energy, 100% clean and capable of heating entire cities thanks to tiny fuel capsules will therefore not become a reality overnight.
On the other hand, this success would prove that it is not just a fantasy of scientists who have their heads in stars… like the Sun. This is perhaps the most important aspect for Alf-Köhn Seeman: “Potential investors will perhaps be convinced that it is worth funding this area of research.”