It was all over rather quickly. On December 5th, in less than 100 trillionths of a second, scientists in California used 192 high-powered lasers to bombard a millimetre-sized capsule of deuterium and tritium, two hydrogen isotopes. The result was one of the technological achievements of the age: proof at last that the well-known effect of nuclear fusion can be harnessed by man, that science can tame the almost limitless and free power of the sun to generate fuel, abundant, pollution-free zero-carbon power.
Fusion energy is produced by combining atoms and is the power source of stars whose immense gravity crushes together atoms of hydrogen to form helium.
In theory we have the basis of an emissions-free source of power, which would help reduce the need for the power plants burning coal and natural gas which pump billions of tons of planet-warming carbon dioxide into the atmosphere each year.
But we have some way to go yet. The decades of research at the Lawrence Livermore National Laboratory culminated in the “holy grail” of fusion, hard evidence of “net energy gain”– more energy produced by a reaction than it takes to initiate – as the hydrogen fused at temperatures close to that found in the sun. Out flowed a flood of neutron particles, with the team reporting “2.05 megajoules of energy to the target, resulting in 3.15 megajoules of fusion energy output” – enough, it has to be said, boil a couple of kettles.
Now a lab experiment must be turned into viable commercial power plants using much faster lasers, able to shoot at a machine-gun pace, perhaps 10 times a second compared to the ten shots a week the apparatus now uses.
And although the energy pulse from the lasers was 2 megajoules, the energy used to charge the laser batteries was 150 times greater. The science has been proven, the technological challenges remain huge.
It may yet be the work of decades – it is far too soon to say we have solved the climate crisis – but a giant step has been taken.