Nuclear fusion is attracting a surge of funding from public and private investors dazzled by the prospect of generating clean energy on Earth from the same reaction that powers the Sun and stars. This week the UK government said it would commit £2.5bn to fusion over five years, including an initial £1.3bn to develop a prototype reactor called Step. Private investment so far exceeds $10bn globally, with the US hosting the best-funded fusion start-ups.
The quest to generate useful energy from the nuclear reaction that fuses light atoms, in contrast to the fission of heavy atoms that powers all existing nuclear power stations, started in the 1950s. Wildly over-optimistic projections made over the past few decades mean that advocates of the technology today have to endure quips that commercial fusion plants are a mirage that always lies 30 years in the future.
Although the engineering challenge turns out to be far greater than anticipated, enough technical progress is being made to suggest that there is a fair chance of fusion power feeding into electricity grids within 15 years or so. Supercomputing and AI, combined with experiments on research reactors, are giving physicists a better understanding of the conditions required to keep a superheated gas plasma at temperatures above 150mn centigrade for long enough to sustain fusion between nuclei of deuterium and tritium. At the same time, materials science is improving the construction of reaction vessels suited to such extreme conditions.