BBC   By Emmet Cole   18 November 2014

The 25-year veteran of the US space agency is the man behind a project called SPS-Alpha, which aims to loft tens of thousands of lightweight, inflatable modules into space. Once there, they will be assembled into a huge bell-shaped structure that will use mirrors to concentrate energy from the sun onto solar panels. The collected energy would then be beamed down to ground stations on Earth using microwaves, providing unlimited, clean energy and overnight reducing our reliance on polluting fossil fuels. The snag? It is unproven technology and he estimates it will take at least $15bn- $20bn to get his project off the ground.

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