The big idea: will fusion power save us from the climate crisis?

One look at your energy bills this winter might have convinced you that the 1950s idea that electricity would, in the near future, become “too cheap to meter” was not so much a false promise as a sick joke. That over-excited claim was prompted by hopes that nuclear fusion – the process triggered in an uncontrolled manner in hydrogen bombs – would soon be harnessed for power generation. In the type of nuclear power we have today, disintegration of radioactive atoms such as uranium produces heat but also a troublesome legacy of radioactive waste that will stay active for millennia. Fusion power plants would instead generate energy using the same process that powers the sun: fusing of the dense nuclei of hydrogen atoms, releasing some of the formidable energy held in the atomic nucleus, with only helium as the byproduct, and without the pollution.

Today the allure of fusion energy lies not so much in its price as its almost negligible carbon emissions, and therefore its potential to save us from the ravages of global heating. But will it arrive in time to stop the planet…