The first nuclear fusion self-sustaining in history has been achieved in a United States Government laboratory, they announced senior officials of the Department of Energy of that country this Tuesday, December 13. The milestone came in an experiment that formed a kind of miniature sun that generates enough power to function without relying on external sources.
Nuclear fusion, the power source of stars, has been experimentally replicated in recent decades by various research teams in developed countries. However, no attempt had succeeded produce more energy than the total used for the process, a goal known as ignition.
This long-awaited “net energy gain” is what the team of scientists from the Lawrence Livermore National Laboratory (LLNL) of California. This is the first demonstration of self-sustaining nuclear fusion, representing a huge leap towards the use of this clean, cheap, safe and virtually unlimited source of energy.
Nuclear fusion inside a miniature ‘sun’
The main referent of this process is the Sun. At its core, the enormous pressure and temperature cause hydrogen atoms to unite and form helium, which releases a large amount of energy.
The recent experiment that replicated this phenomenon took place in the National Ignition Facility (NIF), a facility the size of three football fields belonging to the LLNL. In this enclosure, 192 lasers (the most powerful in the world) aim at a gold cylinder less than two centimeters wide. In the center of it is a spherical capsule containing hydrogen gas.
When lasers heat the cylinder to more than 3 million degrees Celsius, it emits X-rays that bombard the capsule to the point of making it implode, compressing and heating the gas to extreme levels. Thus, it is possible for hydrogen atoms to fuse, form helium and produce energy as our star does.
According to the official report, on December 5, the lasers applied an amount of energy equivalent to 2.05 megajoules (MJ), while the tiny ‘sun’ released 3.15 MJ.
The NIF had repeated the experiment over the past 15 years, and while the results were increasingly promising, they had failed to ignite. For the new scientific feat, they had to make a number of adjustments and even revise the physics behind the process.
“This is a landmark achievement for NIF researchers and staff who have dedicated their careers to making fusion ignition a reality, and this milestone will undoubtedly lead to even more discoveries,” said the US Secretary of Energy, Jennifer M. Granholm.
The source of energy that humanity needs
Unlike nuclear fission (splitting atoms to release energy), which takes place in today’s power plants, fusion creates virtually no radioactive waste or contaminants, nor does it run the risk of producing a chain reaction leading to an explosion, as happened at the Chernobyl and Fukushima plants.
Meanwhile, the raw material used, isotopes of hydrogen called deuterium and tritium. The first abounds in sea water; the other, rarer in nature, can be obtained from the same fusion reaction. That is why it is also known as a relatively cheap and unlimited source of energy.
“This is a huge step forward in believing that this can indeed be the massive, concentrated, high-density source of energy that humanity needs,” he said in a statement. Science Media Centre José Perlado, president of the Guillermo Velarde Nuclear Physics Institute of the Polytechnic University of Madrid.
The LNLL stood out in a announcement that “many advanced scientific and technological developments are still needed” to make this method—called inertial confinement fusion—“simple and affordable for powering homes and businesses.”
“It is clear that there is still a long way to go to make this energy effective,” Perlado stressed.
However, a method that has better potential to produce fusion energy on a large scale is magnetic confinement, which is carried out in tokamak reactors, known as ‘artificial suns’. These experimental systems work in countries like China, South Korea and the United Kingdom.
In fact, the ITER project, which brings together some 30 countries —including those already mentioned— will build a gigantic reactor in France to test the viability of commercial fusion plants.
