Unlock the Editor’s Digest for free
Roula Khalaf, Editor of the FT, selects her favourite stories in this weekly newsletter.
European scientists have set a record for the amount of energy generated from nuclear fusion, another sign of progress in a decades-long effort to produce power by harnessing the reaction that powers the sun.
Researchers at the Joint European Torus facility outside Oxford generated 69 megajoules from a sustained fusion reaction lasting five seconds — enough energy to boil about 70 kettles — surpassing their previous record of 59 megajoules set in 2021.
The latest achievement came in December during the final set of experiments to be conducted at JET, which will be decommissioned this year.
But scientists remain a long way from harnessing fusion power to make it commercially viable. The JET experiment in December consumed far more power than the reaction produced. To build a power station, scientists and engineers must also figure out how to sustain the reactions for longer.
A collaboration between EU member states, Switzerland, the UK and Ukraine, JET has been the world’s largest, most powerful operational “tokamak” machine since it became operational in 1983 and set its first record for energy output in 1997.
The tokamak design, pioneered by Soviet scientists in the 1950s, uses powerful magnets to hold a plasma of two hydrogen isotopes — deuterium and tritium — in place as it is heated to temperatures hotter than the sun so that the atomic nuclei fuse, releasing energy.
“JET’s final fusion experiment is a fitting swansong after all the groundbreaking work that has gone into the project since 1983,” said Andrew Bowie, UK minister of nuclear and networks.
For decades plasma physicists have argued that fusion reactions will one day provide a safe and potentially inexhaustible source of low-carbon energy.
Unlike fission — the process harnessed by nuclear power stations in which atoms are split — fusion produces no long-lived radioactive waste. The isotopes can be sourced in large quantities, and a small cup of the fuel has the potential to power a house for hundreds of years.
Experts welcomed Thursday’s announcement as a further sign of progress.
“JET has operated as close to power plant conditions as is possible with today’s facilities, and its legacy will be pervasive in all future power plants,” said Sir Ian Chapman, chief executive of the UK Atomic Energy Authority, which runs Britain’s fusion programme. “It has a critical role in bringing us closer to a safe and sustainable future.”
JET is due to be replaced by a UK programme, known as the Spherical Tokamak for Energy Production (STEP) project, to be built on the site of a decommissioned coal-fired power station in Nottinghamshire. The government hopes STEP will become one of the first fusion machines in the world to supply power to the grid by the early 2040s.