The action is shifting from the public to the private sector.
Two developments in the coming year will mark a decisive shift from the public to the private sector in the decades-old quest to generate cheap and abundant power from nuclear fusion. The first will be the opening towards the end of 2025, by a private firm, of a machine called SPARC.
This will be the first fusion reactor, public or private, designed to operate at near-commercial scale, with an eventual output of about 140 megawatts (MW). The second will be the non-opening of ITER, the flagship of intergovernmental fusion collaboration, which was scheduled to be ready in 2025. In a hurried announcement in July, that date was postponed.
SPARC is being built by Commonwealth Fusion, a spin-out from the Massachusetts Institute of Technology. Design-wise, it is a tokamak. This is a machine with a toroidal (ie, doughnut-shaped) reaction vessel surrounded by powerful electromagnets which confine and heat the fuel. That fuel is a plasma of two exotic isotopes of hydrogen: deuterium and tritium. These, when suitably heated and confined, undergo a fusion reaction that liberates helium, neutrons—and a lot of energy.
ITER is a tokamak, too, with an intended power output of 500MW. Unfortunately for the 35-country collaboration building it in France, it won’t be ready in 2025. In fact, it is nine years behind schedule, and will not be switched on until 2034. Commonwealth Fusion hopes to reach “q>1”, the point where a reactor releases more energy than is put into it, in early 2026. ITER will not, on its new schedule, reach this point until 2039.
If SPARC works and provides the data that Commonwealth needs to build a full-scale power plant (scheduled for the early 2030s), that will probably be the end of ITER. And even if things do not go to plan for Commonwealth, it is not alone in trying for fusion with private money.
The latest estimate from the Fusion Industry Association, a trade body, suggests that $7.1bn has been raised by more than 40 firms with fusion in their sights. Many are still tiny startups, but several have more than $200m in funding.
Some of these firms are pursuing more exotic approaches than tokamaks, which have, until now, been the tried-and-trusted design for fusion research. General Fusion, a Canadian firm, plans to compress and heat a deuterium-tritium plasma in liquid-metal cavities. A test reactor, in which the compressing metal remains solid, should switch on in 2025.
Helion, in Washington state, proposes a different fuel: a mixture of deuterium and an unusual isotope of helium. Its latest test-bed, Polaris, should also be up and running in 2025. Zap Energy, also based in Washington state, is reviving a once-obsolete approach called z-pinch. ENN, of Hebei province in China, plans to fuse hydrogen and boron. In short, if Commonwealth Fusion fails to deliver, many other start-ups are lining up right behind it. ■
This article appeared in the Science & technology section of the print edition of The World Ahead 2025 under the headline “Fusion power is getting closer”.
Illustration: Science Photo Library
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