Physicists have since the 1950s sought to harness the fusion reaction that powers the sun, but no group had been able to produce more energy from the reaction than it consumes — a milestone known as net energy gain or target gain, which would help prove the process could provide a reliable, abundant alternative to fossil fuels and conventional nuclear energy. The federal Lawrence Livermore National Laboratory in California, which uses a process called inertial confinement fusion that involves bombarding a tiny pellet of hydrogen plasma with the world’s biggest laser, had achieved net energy gain in a fusion experiment in the past two weeks, the people said. Although many scientists believe fusion power stations are still decades away, the technology’s potential is hard to ignore.
Fusion reactions emit no carbon, produce no long-lived radioactive waste and a small cup of the hydrogen fuel could theoretically power a house for hundreds of years. The US breakthrough comes as the world wrestles with high energy prices and the need to rapidly move away from burning fossil fuels to stop average global temperatures reaching dangerous levels. Through the Inflation Reduction Act, the Biden administration is ploughing almost $370bn into new subsidies for low-carbon energy in an effort to slash emissions and win a global race for next-generation clean tech. The fusion reaction at the US government facility produced about 2.5 megajoules of energy, which was about 120 per cent of the 2.1 megajoules of energy in the lasers, the people with knowledge of the results said, adding that the data was still being analysed.
The US department of energy has said energy secretary Jennifer Granholm and under-secretary for nuclear security Jill Hruby will announce “a major scientific breakthrough” at the Lawrence Livermore National Laboratory on Tuesday. The department declined to comment further. The laboratory confirmed that a successful experiment had recently taken place at its National Ignition Facility but said analysis of the results was ongoing. “Initial diagnostic data suggests another successful experiment at the National Ignition Facility. However, the exact yield is still being determined and we can’t confirm that it is over the threshold at this time,” it said. “That analysis is in process, so publishing the information . . . before that process is complete would be inaccurate.”
Two of the people with knowledge of the results said the energy output had been greater than expected, which had damaged some diagnostic equipment, complicating the analysis. The breakthrough was already being widely discussed by scientists, the people added. “If this is confirmed, we are witnessing a moment of history,” said Dr Arthur Turrell, a plasma physicist whose book The Star Builders charts the effort to achieve fusion power. “Scientists have struggled to show that fusion can release more energy than is put in since the 1950s, and the researchers at Lawrence Livermore seem to have finally and absolutely smashed this decades-old goal.”
