IImagine one of those magnets shaped like a horseshoe, but as big as a five-story building and capable of levitating an aircraft carrier. Do you see it? Now think of a microwave oven, also enormous, and so powerful that it is capable of heating soup to 150 million degrees, ten times the temperature of the interior of the Sun. These are two examples that serve to get an idea of the engineering challenges which involves nuclear fusion, an old aspiration of scientists since the sixties. Although they share the last name ‘nuclear’, fusion should not be confused with fission. This consists of separating the atoms of heavy elements, such as uranium or plutonium. Today’s nuclear power plants are fission. In contrast, fusion joins the atoms of the light elements. Well, nothing lighter and more abundant in the universe than hydrogen. If we put two hydrogen atoms together (and apply a huge pressure and temperature), they melt and form a heavier atom: helium. And this process releases energy. How much? One gram of this fuel produces as much as eight tons of oil. No carbon emissions and no danger of radioactive accidents, although it is true that a few neutrons are released that crash into the walls of the reactor and, after a century, they have to be changed because they degrade. As for radioactivity, it is more or less what is produced in a radiotherapy treatment against cancer.
physicist humor
In theory, we could already be enjoying this energy bargain because we understand its fundamentals. In practice, everything is complications. So many that physicists used to tell a joke: “We are thirty years from nuclear fusion… and we always will be.” The main stumbling block is that the accounts do not come out. To date, turning on the ‘artificial sun’ and keeping the plasma hot and confined requires much more energy than will ever be released. That is, the net return is negative. But today no one makes jokes. “Technological advances and private investment indicate that it is going to happen much sooner than we expected. In this decade we will have working prototypes and before 2035 there will be commercial power generation plants by fusion”, says Pablo Rodríguez-Fernández, an engineer from Madrid at the Massachusetts Institute of Technology (MIT), in Boston, where he is participating in one of the projects they lead the world race, the tokamak (as the most common type of these reactors is known) SPARC, developed by the company Commonwealth Fusion Systems with MIT and backed by Bill Gates.
The competition is fierce. There are 35 private companies developing reactors in collaboration with universities and research centers. Half a dozen are in advanced stages and have support such as Jeff Bezos, Google and other great Silicon Valley; sovereign wealth funds of governments, venture capital investors and oil and gas giants that intend to make the leap to clean energy. And then there are the Chinese…
China’s sun heats more…
China’s ‘artificial sun’ has just broken all records. On December 30, it was able to maintain a plasma (a state of matter similar to gas, but so compressed that it becomes an electrically charged fluid) at 70 million degrees for 17 minutes. The plasma behaves wildly, with explosions similar to solar flares. A French team managed in 2003 to stabilize that kind of fiery and creamy ‘vichyssoise’ for six minutes, the previous record. To produce electricity, the plasma needs to be kept under control indefinitely.
One gram of this fuel produces as much energy as eight tons of oil. Now, technology has made it commercially viable.
China is the country that pollutes the most in the world, but it is also the one that invests the most in renewable energy. His recent successes in the field of nuclear fusion are spurring others on. Experts, however, warn that we must wait for the results to be published in scientific journals to discern how much is true and how much is propaganda.
And recent technical advances have unleashed euphoria: a new generation of high-temperature superconductors and artificial intelligence applied to mathematical simulation models, among others. Rodríguez-Fernández is the lead author of the paper showing that the SPARC reactor can produce ten times more energy than it consumes. This, in essence, validates its commercial viability. What has happened to make it feasible now?
Until a few years ago, the bulk of the research was monopolized by the ITER project, a grandiose initiative with public funds in which 35 countries participate (including Spain) and which has spent 25,000 million dollars. It was born with the end of the Cold War, when Presidents Ronald Reagan and Mikhail Gorbachev agreed to collaborate on a project that would unite humanity. «But the technical limitations of the time meant that a pharaonic structure was chosen. A huge reactor that, thanks to its dimensions, can generate the magnetic fields necessary for fusion and is being built in the south of France. With the new superconductors, however, magnetic fields can be created that are the same or more intense, but on a much smaller scale, thus lowering costs”, explains Rodríguez-Fernández.
the same as the vaccine
ITER is also weighed down by international bureaucracy. “And it is merely experimental, not commercial. To arrive at commercial models with this technology, we would have to wait until 2060. However, ITER has been very positive because we have all benefited from its research. The tokamak-type reactor, although much smaller, has very robust foundations behind it.” More than 200 have been manufactured throughout history. Most are donut-shaped and consist of an evacuated chamber surrounded by a very strong magnetic field to cage the plasma. Hydrogen is injected, to which electrical pulses are applied. The gas heats up and the atoms fuse. Other companies are taking risks with variations on the tokamak or with very different models. “In a way, nuclear fusion is happening like the vaccine race, which was a success because scientific collaboration and strong competition were combined. The international community working on the merger is also very supportive, although with the arrival of private capital, more care is being taken when disclosing certain information that affects intellectual property.
Will fusion arrive in time to curb climate change? “That’s the big question. On a personal level, what motivates me the most is being able to do something useful for the future of humanity. But we need to act now. We must continue betting on renewable energies while fusion arrives, which should be operational in a decade, but we must not disdain fission, which is our best bet in the short term to achieve zero emissions. It is not good to put all your eggs in the same basket,” warns Rodríguez-Fernández.
Bezos
The most powerful bet
General Fusion, in Vancouver (Canada), is the company that Jeff Bezos bets on and develops a high-power reactor. The plasma is injected into a cavity lined with liquid lead and lithium. Pistons compress it for twenty milliseconds to heat it up. The prototype will be finished in 2025.
Goal: electricity in ten years
TAE Technologies (California) calculates that in five years it will be able to maintain stable fusion reactions and in ten it will have a commercial prototype of its reactor. The company is financed by Alphabet (the parent company of Google) and sovereign wealth funds.
Bill Gates
The low-cost reactor
Bill Gates and the Italian oil company Eni support the project of Commonwealth Fusion Systems (Boston), a start-up made up of engineers and physicists from MIT, the institution that develops the SPARC test reactor, a ‘sun low cost‘ ($400 million) that harnesses superconducting technology.
China
The one who resists the most
The Chinese EAST tokamak has managed to heat a loop of plasma to temperatures five times higher than that of the sun (70 million degrees) for 1056 seconds. It is a world record. China has invested one billion dollars in this experimental reactor located in Hefei.