Nuclear fusion’s supporters describe it as the “holy grail” of clean energy: a technology that could theoretically provide near limitless, zero carbon power.

Fusion produces no long-lived radioactive waste, emits no carbon and has the potential to produce vast amounts of energy. Now scientists are racing to find a way to turn a century of experiments into a commercially viable power source.

How does it work?

Nuclear fusion is the reaction that powers the sun. It involves heating two hydrogen isotopes — normally deuterium and tritium — to such extreme temperatures that the atomic nuclei fuse, releasing helium and vast amounts of energy in the form of neutrons.