Comment: Nuclear fusion has been described by the World Economic Forum as being the Holy Grail of energy, a technology that will provide unlimited, cheap, clean power. Fusion is the process that powers the Sun and the stars. The often-quoted vision for fusion is that it will provide clean energy in perpetuity, like our sun does. This vision has inspired fusion research since the 1940s. There was a joke in scientific circles, about when fusion energy would become applicable.