Extreme machines give us endless energy
Fusion is a clean, safe and inexhaustible source of energy, but to mimic the sun, the world's most advanced machines are required. Now physicists are taking the next step towards fusion by filling a reactor with power plant fuel.
Fusion energy without neutron radiation – that goal wants the company TAE Technologies to achieve by getting ordinary hydrogen cores, protons, to merge with boratoms.
When a bore-11 core picks up a proton and emits fusion energy, the bornue is converted into three helium cores. No neutrons are emitted during the merger, so the reactor will not be radioactive.
Globular reactor with cheap magnets
The English company Tokamak Energy has built a small globular tokamak reactor with a diameter of only two meters. Last year, it was heated up to 15 million degrees using a fusion fuel. The next step will be to increase the temperature to the 100 million degrees required in a power plant.
Usually, fusion reactors use superconducting metallic magnets that need to be cooled with helium. Still, this reactor is so small that you can use superconducting ceramic magnets that are cooled with cheap liquid nitrogen.
Fusion is like lighting a fire with wet wood. The positively charged hydrogen cores repel each other and do everything they can to avoid contact. Therefore, the world’s most extreme machines are required to force the reluctant hydrogen atoms together by either extremely high temperature or exceedingly high pressure.
When successful, the copious amounts of energy that the merger develops can give us clean and cheap electricity.
The vision of utilizing the energy of the fusion goes back decades. Now physicists are taking another step on the road to the energy source of the future. The European reactor Jet at the end of 2020 is filled with heavy and superheavy hydrogen.
Jet is the largest of the current experimental reactors and the only one built to handle real power plant fuel. The other reactors use only heavy hydrogen, which gives too few fusions to be used in a power plant. The experiments on Jet will be a taste of the next generation of fusion reactors.
The eight-times larger Iter reactor is being built in France. The trials of the new flagship, which begins in 2025, will create the first self-propelled fusion process – what physicists call ignition – and thus generate an enormous surplus of energy.
The possibilities of fusion energy are enormous. The raw materials are heavy hydrogen, which is extracted from seawater, and superheavy hydrogen, which is produced from lithium. This makes fusion energy a virtually inexhaustible source of energy.
Seawater is there, so it will last forever, and the known lithium reserves will last at least a thousand years. However, the technical challenges are enormous.
Laser competes with reactors
Most fusion plants follow one of two main paths to fusion energy. One is laser fusion, an area where the United States is at the forefront. Energy-rich laser beams bombard a hydrogen pellet from different directions and compress the hydrogen with such force that it merges into helium.
At the huge laser plant, NIF in 2014, one and a half times more energy was extracted from a small hydrogen pellet than the amount of energy the laser rays pumped into the fuel. However, physicists did not achieve their goal of having the fusion process continue on its own after it was initiated.
The reactors have become the first choice, and here there is fierce competition between two technologies. In both techniques, the hydrogen is heated to a plasma redness – in which the nucleus and electrons are separated – and keeps it trapped in a strong magnetic field so that it does not touch the reactor wall and cool down.
One type is classic reactors such as Jet and Iter, so-called tokamakers. It is the easiest type of reactor to build. The disadvantage is that a tokamak manages to hold the fusion fuel in the magnetic cage for a maximum of one hour at a time. Then the reactor must be emptied, and new fuel pumped in and ignited. It must be done quickly in a power plant so that consumers do not experience operational disruptions.
The second type of reactor is the stellator, where the magnets are rotated in irregular shapes to create an extremely even magnetic cage that can be maintained for several years. Here you can continuously refill new fuel in the reactor, much like when you shovel more coal into a boiler.
However, the irregularly shaped magnets make it extremely difficult to construct the reactor. In 2003, it was close to the Germans abandoned the construction of the world’s first large stellar orator Wendelstein 7-X. Fortunately, they struggled on; the reactor is now running like smear and has already, after a couple of years of trying to keep the fuel contained for 100 seconds at a time.
You have a bit left to the world record of six and a half minutes, set by the small French tokamaker West in 2003, but German physicists believe that you will be able to keep the fuel contained for half an hour at a time in the Wendelstein 7-X reactor.
Red hot plasma makes its way out of the cage
None of the existing most giant experimental reactors will be able to produce more energy than they use to heat up the fuel. Together, however, the reactors show the challenges that need to be solved to pave the way for genuine fusion power plants.
Jet will give scientists invaluable experience in the form of experiments with real power plant fuel, which consists of both heavy and superheavy hydrogen. The reason that physicists have so far been restrictive in using superheavy hydrogen in the reactors is that superheavy hydrogen is a radioactive substance that requires expensive safety devices.
The biggest challenge, however, is to keep the fusion plasma in place for a long time in the so-called containment. The red-hot and turbulent fuel is continuously trying to break out of the magnetic grip and get in touch with the reactor wall. Therefore, the reactor ring must be contained in powerful and stable magnetic fields.
The aging Jet Reactor has only common magnets and cannot keep the fuel encased for more than a few seconds. In 2020, however, a more efficient magnetic cage is tested in Japanese toka makeJT60-SA, which has been upgraded with superconducting magnets that will keep the fuel encased for 100 seconds at a time.
To take the next step towards the clean energy source of the future, the researchers are working to construct the world’s largest and most complex machine at a price of just over SEK 200 billion.
The Iter reactor is being built in southern France through cooperation between the EU, the US, Russia, Japan, China, India, and South Korea. The building is high as a 15-story building, and the reactor will weigh 23,000 tons. The reactor ring, which has a diameter of 19.4 meters, will be surrounded by massive, up to 25-meter superconducting magnets.
The large reactor will pass the critical milestone on the way to power plants and ignite the fuel so that the fusion process continues by itself when the reactor’s heater is switched off.
In the hot plasma, the extremely warm helium cores collide from the fusion with the hydrogen cores and heat them up and force them into new fusion processes. Energy production continues as long as the reactor is supplied with fresh fuel and as long as the magnetic cage encloses the fuel. The goal is to maintain containment for one hour at a time.
Trials of heavy and superheavy hydrogen power plant fuel beginning in 2035. Then the ignition shall make it possible to produce ten times more energy than the reactor uses to heat the fuel. Later, the energy surplus will be increased to 30 times the amount of energy added.
Iter creates fusion energy with extreme heat and cold.
It is still uncertain whether the successor to Iter becomes a tochamak or a stellarator. The results of Wendelstein 7-X can be so good that the stellarator becomes the victorious technology – or one of the options that private companies test on a tiny scale to outcompete the giants.
Seawater replaces coal
Around 2060, the first fusion power plant is expected to supply power to the mains. No matter which version wins, fusion will be a safe source of energy because there is no risk of unbridled chain reactions as in a nuclear power plant. As soon as the supply of fuel ceases, the processes in the reactor subside.
Fusion also does not leave behind any highly radioactive waste that needs to be stored for 100,000 years. Helium is the only residue.
Heavy hydrogen from 40 liters of seawater and superheavy hydrogen from five grams of lithium – equivalent to the contents of a mobile phone – can provide as much energy as 40 tons of carbon and pollute either the air or emit carbon dioxide. It could give fusion the lead role in the climate-neutral energy supply of the future.