The dream of nuclear fusion, a clean, inexhaustible and cheap form of energy, is closer today. As the US press reported over the weekend, this Tuesday the US Secretary of Energy, Jennifer Granholm, has confirmed “a major scientific breakthrough”: a team from the Lawrence Livermore National Laboratory (LLNL) in California has achieved for the first time achieve the so-called ‘ignition’: fusing atomic nuclei producing more energy than it costs to induce that reaction.
US scientists take a key step towards nuclear fusion, a clean and unlimited source of energy
It has been possible to “briefly simulate a star”, summarized the US Undersecretary for Nuclear Security, Jill Hruby. This advance “will enter the history books,” summarized Granholm. Now, for the first time –since this objective began to be pursued in the 1950s– a net energy gain has been achieved. The advance, however, has not yet been published in any scientific journal, so there is no independent validation of it.
“This has come after 60 years of experimentation,” said Jill Hruby to underline the long scientific path followed up to now. “It has come from the accumulated work that has been done before. And the tireless effort of hundreds of people.”
The LLNL researchers consumed 2.1 megajoules in triggering the fusion of nuclei and would have gotten 2.5 megajoules: a net gain of 0.4 megajoules. In recent days there was even talk of 3 megajoules, which would raise the net gain to 0.9 megajoules.
“Ignition is the first step,” explained the LLNL scientists. From here “many things must be done to commercialize this energy”, they added. Among them, you have to get many ignitions per minute and the “resistant” material to be able to do it. “It will take a decade of investment, but I don’t think it will be six or five,” they have predicted.
Information about these results had been populating the emails of researchers specialized in nuclear physics from half the world for days (the milestone would have been reached on December 5). Now, it has been confirmed in a press conference that has aroused enormous international expectation.
This advance has been hailed by the Biden Administration as a great success of scientific projects financed with public money. The announcement places the US at the head of a race in which the great powers compete.
The milestone has been carried out in an LLNL infrastructure called the ‘National Ignition Facility’ (NIF, in its English acronym). With a cost of 3,500 million dollars of federal funds, nuclear weapons are tested in that compound, among other areas.
A ‘little Sun’
Nuclear fusion is the same process by which the Sun and other stars produce energy. It basically consists of the fusion of the nuclei of atoms of light elements. In the case of the Sun –and the LLNL experiment–, hydrogen atoms or their isotopes: deuterium and tritium.
The solar radiation that reaches Earth in the form of light and heat comes from this process of nuclear fusion. In the case of the Sun, this fusion of the nuclei of hydrogen atoms converts them into helium. The mass of helium is less than that of hydrogen atoms, therefore, following Einstein’s famous equation that shows the equivalence between mass and energy (E=mc²), that mass of hydrogen that results from its fusion in helium it is transformed into energy.
Until now, and for decades, inducing nuclear fusion on Earth required physical conditions that consumed more energy than that reaction produced. The specialists consulted by the media in recent days agree in assessing the milestone, but warn that there is still a long way to go until nuclear fusion energy can be used in a controlled manner and supply electricity to the grid.
Unlike fossil fuels, nuclear fusion does not create greenhouse gases; It also does not produce radioactive waste. To date, and in the face of nuclear fusion, the only viable nuclear energy is based on the opposite process: the fission of nuclei (the word fission is from the same family as fissure).
the energy of fission it is achieved by splitting the nucleus of atoms of heavy elements, such as uranium and plutonium. It is a dirty source of energy –because it generates radioactive waste that is harmful to life– and dangerous –because it is produced in atomic plants subject to accidents, such as those at Chernobyl or Fukushima–, although it does not emit greenhouse gases (such as CO2) in its obtaining.
To get the hydrogen nuclei to melt, a high amount of energy is necessary to bring them so close that it turns them into plasma (a kind of electrically charged gas). In the case of the achievement confirmed today, the researchers have heated the atoms by impacting the beam of one of the largest lasers in the world on the hydrogen isotope particles: this causes them to implode in the form of plasma, making them more dense, thereby fusion is caused. Hence this process, in which high temperatures play an essential role, is also called thermonuclear fusion.
In addition to the method used in the United States, an international megaproject – made up of 35 countries included – is working on a thermonuclear alternative to lasers, called magnetic confinement fusion. In this method, it is a magnetic field that traps the electrically charged particles in the plasma.
The device that generates this magnetic field has a toroidal shape. It is called Tokamak and it was conceived in the 50s by Soviet engineers. that is precisely the ITER, the international experimental reactor whose construction began in 2013 in Cadarache (France) and whose completion is expected by 2025. China, the European Union, the United States, Russia, India, Japan and South Korea, among other countries, collaborate in this project. The committed budget exceeds 22,000 million euros, mainly public money.