Fraunhofer Institute for Laser Technology ILT
A safe, virtually inexhaustible source of energy for the future
Human life is based on solar radiation. Its energy comes from the fusion of hydrogen into helium, a process that has been going on for 4.6 billion years. During fusion, two light atomic nuclei fuse to form a heavier nucleus, releasing enormous amounts of energy. This inexhaustible, climate-neutral energy source – available 24/7 – should be harnessed on Earth in the future. Research institutions, industrial companies and start-ups around the world are working round-the-clock on concepts and technology modules for nuclear fusion power plants.
In particular, the fusion of the hydrogen isotopes deuterium and tritium to form helium has proven to be feasible. In order to trigger fusion, the so-called ‘Coulomb wall’ – a strong repulsive force between the nuclei – must first be overcome. This requires temperatures of around 150 million degrees Celsius. Under these conditions, the nuclei come within a femtometer of each other and under the influence of an even stronger nuclear force, which causes the isotopes to fuse into helium nuclei, each with two protons and two neutrons. One neutron remains. In total, the deuterium and tritium isotopes are heavier than the helium nucleus. According to Albert Einstein's theory of the equivalence of mass and energy, fusion releases binding energy, which amounts to 17.6 megaelectronvolts (MeV) or 9.2 x 104 kWh per gram. To put this into perspective, 1 kg of this deuterium-tritium mixture contains as much energy as 55,000 barrels of diesel or 18,630 tons of brown coal.
