A leading British scientist has claimed that the power stations of the future will operate on nuclear fusion.

Professor Brian Cox told an energy debate in the UK that he believed nuclear fusion rather than nuclear fission could be the answer to global energy demands by the end of the century.

Asked what form of energy he thought would power the world in 100 years he answered: “I think it will be nuclear fusion without a doubt.”

He said great strides were already been made at the international fusion project Iter, a collaboration between Europe, China, India, Japan, Korea, Russia and the US.

Prof Cox said Iter was developing a prototype commercial reactor involving plasma, which needs to be heated to scorching temperatures of as much as millions of degrees Celsius.

“The fusion project aims to have plasma in it and doing research on how that plasma works by 2019. It’s under construction now. Nobody I’ve spoken to on that project believes that there will be any show-stopping problems with it.

“It is essentially a commercial reactor design give or take, so by the mid-2020s we should have essentially a working prototype commercial reactor.”

He added: “The cost is all infrastructure cost, the fuel is free and effectively infinite. Unless there’s some engineering challenge we don’t know about then surely by the end of this century, fusion power stations should be delivering essentially unlimited energy, not free because it costs a lot to build the reactors.”