Breakthrough in nuclear fusion: what do new results mean for the future of “infinite” energy?

Lawrence Livermore National Laboratory announced a major breakthrough in nuclear fusion by using powerful lasers to generate 1.3 megajoules of energy – about 3% of the energy found in 1 kg of crude oil.

Nuclear fusion has long been considered the energy of the future – an “infinite” source of energy that does not depend on the combustion of carbon. But after decades of research, it has yet to deliver on its exciting promise.

How much closer does this new breakthrough bring us to the desired results? Here’s a quick rundown to put this new scientific advancement into perspective.

What is nuclear fusion?

There are two ways to use nuclear energy: fission, which is used in current nuclear power plants, and fusion.

During fission, heavy uranium atoms are broken down into smaller atoms to release energy. Nuclear fusion is the reverse process: light atoms are converted into heavier atoms to release energy, the same process that occurs in the sun’s plasma core.

A fusion reactor increases the output: the reaction that is triggered must produce more energy than is required to heat the fuel plasma to generate energy – the so-called ignition. Nobody has done that yet. The current record was set in 1997 by the Joint European Torus in the UK, where 16 megawatts of electricity were generated by magnetic fusion but 23 megawatts were required to trigger it.

In the fusion chamber of the DIII-D tokamak, San Diego, USA. Rswilcox, CC BY-SA

There are two ways to achieve nuclear fusion: magnetic confinement, in which the plasma is confined with strong magnets for very long periods of time, and inertial confinement, in which very strong and short laser pulses are used to compress the fuel and start the fusion reaction .

In the past, magnetic fusion was preferred because the technology required for inertial fusion, particularly lasers, was not available. Inertial fusion also requires much higher gains to compensate for the energy consumed by the lasers.

Inertia constraint

The two largest inertial projects are the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in the United States and the Laser MégaJoule in France, whose applications are primarily military and funded from defense programs. Both institutions simulate nuclear explosions for research purposes, but the NIF also conducts energy research.

The NIF uses 192 laser beams that generate a total of 1.9 megajoules of energy over a period of a few nanoseconds to trigger the fusion reaction. The fuel is located in a metal capsule with a diameter of a few millimeters which, when heated by lasers, emits X-rays that heat and compress the fuel.

It was this process that reached the groundbreaking energy production of 1.3 megajoules on August 8, 2021, the highest value ever measured by the inertial method, i.e. the closest thing to ignition.

The total gain of 0.7 corresponds to the record JET achieved in 1997 with magnetic confinement, but in this case the fuel absorbed 0.25 megajoules of energy and produced 1.3 megajoules: so the fusion produced a good portion of the heat required for the reaction and approached the ignition point.

Still, a reactor must have much higher profits (more than 100) to be economically attractive.

Magnetic confinement

The approach of magnetic confinement promises better development prospects and is thus the preferred way of generating energy so far.

The vast majority of research focuses on tokamaks, fusion reactors invented in the USSR in the 1960s, in which the plasma is confined by a strong magnetic field.

ITER, a demonstration reactor under construction in southern France involving 35 countries, uses the tokamak configuration. It will be the largest fusion reactor in the world and should show a profit of 10 – the plasma is heated with 50 megawatts of power and should generate 500 megawatts. The first plasma is now officially expected by the end of 2025, with a fusion demonstration expected in the late 2030s.

The UK recently launched the STEP (Spherical Tokamak for Electricity Production) project, which aims to develop a reactor that will be connected to the grid in the 2040s. China is also pursuing an ambitious program to produce tritium isotopes and electricity in the 2040s. Finally, Europe plans to open another tokamak demonstrator, DEMO, in the 2050s.

Another configuration called a stellarator, like the German Wendelstein-7X, shows very good results. Although stellarator powers are lower than what a tokamak can achieve, its intrinsic stability and promising recent results make it a serious alternative.

The future of merger

Private nuclear fusion projects have now been booming in recent years. Most of them envision a merger reaction over the next ten to 20 years and have together raised $ 2 billion in funding to outperform the traditional development sector.

Two different application scenarios of nuclear fusion compared to wind, solar and nuclear fission. G. De Temmerman, D. Chuard, J.-B. Rudelle for Zenon Research, author provided

While these initiatives may use other innovative technologies to achieve the merger and thus could very well deliver operational reactors quickly, deploying a fleet of reactors around the world will certainly take time.

If development follows this accelerated path, nuclear fusion could account for around 1% of global energy needs by 2060.

While this new breakthrough is exciting, one should keep in mind that fusion will not be a source of energy until the second half of the century at the earliest.

This article was originally published in The Conversation

Greg De Temmerman is an Associate Researcher at Mines Paris Tech and Managing Director of Zenon Research.