Could we finally be about to crack this source of potentially unlimited clean energy - thanks in part to a plethora of private sector tech startups?

Laurence Knight travels to one such company, Tokamak Energy in the UK, to hear from plasma physicist Melanie Windridge. Meanwhile the BBC's David Willis reports on the string of secretive new fusion initiatives along the Pacific Coast, and the Silicon Valley money backing them.

Plus, could fusion energy open the way to the economic abundance and space travel portrayed in Star Trek? Laurence speaks to Trekonomics author Manu Saadia.

(Picture: Plasma inside a Tokamak fusion reactor; Credit: Tokamak Energy)