Climate hope as scientists in UK set fusion record

Scientists in Britain announced Wednesday they had smashed a previous record for generating fusion energy, hailing it as a "milestone" on the path towards cheap, clean power and a cooler planet.

Nuclear fusion is the same process that the sun uses to generate heat. Proponents believe it could one day help address climate change by providing an abundant, safe and green source of energy.

A team at the Joint European Torus (JET) facility near Oxford in central England generated 59 megajoules of energy for five seconds during an experiment in December, more than doubling a 1997 record, the UK Atomic Energy Authority said.

That is about the power needed to power 35,000 homes for the same period of time, five seconds, said JET's head of operations Joe Milnes.

The results "are the clearest demonstration worldwide of the potential for fusion energy to deliver safe and sustainable low-carbon energy", the UKAEA said.

The donut-shaped machine used for the experiments is called a tokamak, and the JET site is the largest operational one in the world.

Inside, just 0.1 milligrammes each of deuterium and tritium -- both are isotopes of hydrogen, with deuterium also called heavy hydrogen -- is heated to temperatures 10 times hotter than the centre of the sun to create plasma.

This is held in place using magnets as it spins around, fuses and releases tremendous energy as heat.

Fusion is inherently safe in that it cannot start a run-away process. 

Deuterium is freely available in seawater, while tritium can be harvested as a byproduct of nuclear fission.

Pound for pound (gram for gram) it releases nearly four million times more energy than burning coal, oil or gas, and the only waste product is helium.