There is a joke among physicists and engineers specializing in nuclear fusion that clean, inexhaustible and cheap energy from this procedure is 30 years away… and always will be. None of the experts doubt that this is one of the energy sources of the future, perhaps even the energy source of the future. But that future is still distant, and the announcement scheduled for today in the US that the media is highlighting is not going to bring it closer.
Let’s remember the basics (more on nuclear fusion here): it is about creating devices that simulate the natural process that takes place in the Sun, the fusion of hydrogen nuclei (or its isotopes deuterium and tritium) to form helium and release energy. For this, it is necessary to heat the hydrogen to millions of degrees, so that the atoms lose their electrons and a cloud of nuclei is formed, a plasma that allows the fusion of those nuclei. The fusion emits radiation in the form of neutrons, but does not generate radioactive material waste. There are two main types of fusion reactors, tokamakshaped like a doughnut, and the stellarator, similar to a Moebius strip (of the latter we have one in Spain, the second largest in Europe, at the CIEMAT). In both cases the plasma is kept confined by magnetism.
I think what follows is better explained in the form of questions and answers:
A portion of the National Ignition Facility facilities in California. Image from Lawrence Livermore National Laboratory.
If everything is so fabulous, why don’t we already have fusion power?
Fusion power doesn’t have any physical fundamentals problems, but it does have many engineering ones. The first and most essential is achieve a net energy gain, that is, more energy is obtained than what must be invested to achieve fusion. But it is not the only one: according to the experts, important improvements still have to be achieved in the protection of the reactor against neutrons, in the stability of the plasma and others.
What is going to be announced today in the US?
According to what has been leaked to the media, what will be announced today is that the experimental reactor of the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in California has managed to achieve a net energy gain of one. In other words, the energy invested equals the energy released. This is achieved when the so-called fusion ignition is reached, at which point the process is self-sustaining. But as we will see, there is a small catch.
Is this the first time this has been achieved?
In fact, no. Already in 2021 the NIF researchers they announced that they had achieved it, and published it. But then it was not possible to repeat. It would be expected that what is going to be announced today is that they have finally managed to replicate it. We will have to wait for the details.
Will the US reactor be the final solution?
According to experts, no. The LLNL reactor is a different type of reactor than the tokamak and the stellarator that does not use magnetic confinement of the plasma, but the so-called inertial. It involves bombarding a pellet or cylinder of deuterium and tritium fuel with high-energy rays, usually lasers. The NIF uses 192 simultaneous lasers. But although this is a kind of valid experimental solution, it is not practical for future commercial power plants. First, you would have to make those little balls or pellets on an industrial scale. Second, it would require a machine that was continually replenishing them, with lasers firing in bursts like warships. Star Wars. And for that tiny pellet, like a pin, you need an installation that occupies an entire building. And finally, there is also the trap.
What’s the catch?
The trap is that, predictably, what the researchers have achieved is an energy gain of one relative to the energy provided by the 192 lasers when incident on the pellet. But these lasers are very inefficient; In reality, the energy needed to make them operate is much greater than the one they inject into the pellet made out of fuel. If the figures don’t fail me, I think that only about 10% of the energy of the lasers ends up reaching the pellet. Therefore, for there really to be a net energy gain in the whole process that would open the door to commercial use as an energy source, it would be necessary for the energy obtained in fusion to not only equal that of lasers, but also was several times larger.
So what are the closest options to a future fusion power?
In the French town of Cadarache, it has been built, for so many years that we don’t even remember how many, ITER, the largest tokamak in the world, a collaborative project between the European Union, USA, Russia, China, India, Japan, South Korea and Switzerland. ITER will not be a commercial facility, but is intended to be the forerunner of future commercial facilities. In 2020 the assembly finally began tokamak, and it is expected that it will be completed and plasma will begin to be injected in 2025, although these forecasts should be taken with a grain of salt. Under current plans, in the 1930s ITER could be operating, and it is estimated that perhaps in the 1950s we could finally have commercial facilities running.
Apart from what we know, there is what we do not know: the unknown Chinese. Recently China has announced the construction of a huge plant that aims to generate fusion power by 2028. This is a date that experts have considered a wild fantasy based on the progress of these technologies in the West; but you know, China is always unknown.
So far, this is to be expected from this afternoon’s announcement. If there are any major variations an update will follow.