Climate-neutral, cheap energy that can be produced in masses: That sounds like science fiction – and yet it may be closer than you think. US scientists have managed to generate more energy than they use by fusing atomic nuclei.

It is a scientific sensation: For the first time, researchers have succeeded in nuclear fusion that produces more energy than is consumed. This could fundamentally change the world in a few years.

Scientists in the USA have made a historic breakthrough in the field of nuclear fusion. For the first time, the fusion of atomic nuclei produced more energy than was consumed, as US Secretary of Energy Jennifer Granholm announced in Washington on Tuesday. “Put simply, this is one of the most impressive scientific achievements of the 21st century,” said Granholm.

The results, obtained by a team of researchers at the state’s National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California, mark a milestone in the discovery of a new energy source. In a few years, nuclear fusion could possibly be used to generate electricity in huge quantities in a climate-neutral and safe manner. However, there is still a long way to go before mass production can continue due to major technical hurdles.

Almost a year ago, advances in nuclear fusion were announced at the institute. A research team reported in the journal “Nature” at the beginning of the year that the ignition of the plasma was achieved. This ultimately results in the fusion reaction becoming self-sustaining. In the nuclear fusion reactor, the fuel is in the form of plasma – this state of aggregation is created when a gas is extremely heated.

Both nuclear power and nuclear fusion derive energy from the binding forces of atomic nuclei. With nuclear power, however, large atoms are split, radioactive waste is produced, among other things, and there is a risk of serious accidents. In nuclear fusion, on the other hand, small atomic nuclei are fused – fused – into larger ones, the technology is considered clean and safe. This form of energy generation is similar to what happens in stars like the sun.

An overview of how nuclear fusion works, what advantages it brings and the state of the art:

In nuclear power plants, atomic nuclei are split to generate energy. In contrast, in nuclear fusion, two light atomic nuclei (hydrogen) are fused into one heavy one (helium). This also releases energy. This process takes place in the stars, including the sun.

Nuclear fusion is only possible on Earth by heating matter to very high temperatures of over 100 million degrees. “So we have to find ways to isolate this extremely hot matter from anything that could cool it down,” explains Érik Lefebvre, project manager at the French Atomic Energy Agency (CEA). One method is to contain the fusion reaction with magnets.

In a giant donut-shaped reactor, light hydrogen atoms (deuterium and tritium) are heated until they reach the state of a plasma, a very low-density gas. Magnets confine the swirling plasma, preventing it from touching the walls of the chamber as the atoms collide and begin to fuse. This type of reactor is used in the major international project ITER, currently under construction in France, and in the Joint European Torus (JET) near Oxford in the UK.

A second method is inertial fusion. Here, high-energy lasers are simultaneously aimed at a thimble-sized cylinder of hydrogen. This technique is used in the French Megajoule Laser (LMJ) and the world’s most advanced fusion project, the National Ignition Facility (NIF) in California.

These projects are primarily concerned with demonstrating the physical principles of fusion. With the other reactor types, on the other hand, attempts are being made to test future fusion reactors.

For decades scientists have been trying to find a way to use nuclear fusion to generate more energy than is needed to start the reaction. The researchers at the NIF are said to have succeeded in achieving this net energy gain, as reported by the “Financial Times” and the “Washington Post”. However, there is still a “very long way” to industrial and profitable use of nuclear fusion, Lefebvre dampens expectations and expects another 20 to 30 years of research and development.

Large-scale nuclear fusion could transform energy production around the world. Unlike nuclear fission in nuclear power plants, there is no risk of a nuclear accident with fusion. “If a few lasers are missing and not fired at the right moment, or if the confinement of the plasma by the magnetic field is not perfect, the reaction simply stops,” says Lefebvre.

Nuclear fusion also produces far less radioactive waste and emits no greenhouse gases. “It’s a zero-carbon energy source that produces very little waste and is extremely safe,” Lefebvre says, seeing nuclear fusion as “the future solution to the world’s energy problems.” However, the development is not yet so advanced that nuclear fusion could make a contribution to limiting climate change.