Nuclear fusion success inspires optimism, but also calls for caution

The announcement made this Tuesday (13) by the Department of Energy of the United States that for the first time a nuclear fusion experiment obtained more energy than it consumed inspires a lot of optimism, but also recommends caution.

The result was obtained by a team from the Lawrence Livermore National Laboratory, in California, and consists of a proof of principle that the production of energy by the same method that makes the sun shine can be mastered by human beings for peaceful purposes. The promise is abundant, clean and carbon-free energy, which explains its revolutionary character.

For six decades now, experiments have sought to obtain the result now achieved. Several techniques and devices were used, with large investments made in countries such as China, Japan and European nations, in addition to the USA.

In all of them, a common result: even when nuclear fusion was reached, that is, the system managed to get hydrogen atoms to stick to each other, releasing part of its mass in energy, the energy consumption for this to happen was larger than the reaction produced back.

By August 2021, NIF (National Ignition Facility) personnel inside the Lawrence Livermore had managed to come close, producing 70% of the energy consumed with their system, which uses a technique known as inertial confinement fusion.

After improving the design of the experiment, the scientists returned to the load in the first hour of December 5 of this year, California time. At 1:02 am, 192 high-powered lasers were fired at a small capsule where “heavy” hydrogen atoms (known as deuterium and tritium, are versions of this chemical element that have one and two neutrons in their nucleus, in addition to the proton that features).

The lasers promoted the crushing of the matter, which became superheated to millions of degrees (a temperature higher than that of the interior of the Sun) and led the atoms to fuse, converting themselves into helium. On the Sun, this happens naturally, courtesy of the star’s immense gravity, which puts pressure on its interior. In the laboratory, things get more complicated.

Well then. In the smallest fraction of a second that the experiment remained on, 4% of the hydrogen atoms were converted into helium. And, in the jargon of scientists, the reaction has reached the ignition point — where, in principle, it would be possible to maintain it sustainably.

The most important number of the entire experiment: By injecting the target with 2.05 megajoules of energy via the lasers, the fusion produced 3.15 megajoules back—a net gain of 53.6% (more than the preliminary numbers that the Financial Times newspaper had had access to).

If that seems like little, keep in mind that, to date, in all experiments, there has never been even a net gain. From now on, there is no more talk about “if nuclear fusion works”. The discussion about when begins.

It was a running joke among academics that a practical fusion reactor is 30 years in the future — but that was 60 years ago. With the experiment, that count will finally start to regress.

During the press conference in which they presented the results, representatives of the Department of Energy highlighted that there is still a lot of research and development to take what is currently an experimental arrangement to a commercial plant, demanding a lot of public and private investment. Time continues to be estimated in decades or, at least, one of them (goal set by the US government itself during Joe Biden’s management).

This means that, despite the justified optimism, it is necessary to adjust expectations. First, it will be necessary to replicate the experience, confirming that there is no systematic error and that it was not the result of an accident. Then optimize it to the point of pointing a clear path to the design of a practical nuclear fusion power plant. Finally, implement a pilot program that leads to a commercial stage.

The same path must be taken by means of other methods of obtaining nuclear fusion, developed by other groups around the world. The good news: a new phase of the merger race is now starting.

The bad: in practice, we still cannot count on this new technology for the drastic and rapid reduction of carbon emissions required in the coming years to contain the increasingly less avoidable climate breakdown. No one will be able to sit on their own hands waiting for the merger to become a reality in order to pursue national targets for cuts and promote changes in the energy matrix.

On the other hand, the revolutionary potential of producing energy in the fashion of the Sun is no longer a mirage, a matter for futurists. We’re talking about something powered by hydrogen (the most abundant and available element in the Universe), which doesn’t emit carbon, is safe (there’s still radioactivity involved, but nothing like plutonium will come out of those reactors) and, unlike other forms of clean energy, like wind and solar, it does not depend on local environmental conditions — therefore applicable anywhere in the world.

There are still many technical challenges to be overcome, but today a sustainable future with abundant energy is no longer science fiction.