It may sound like a sci-fi vision, but Japan's space agency is dead serious: by 2030 it wants to collect solar power in space and zap it down to Earth, using laser beams or microwaves.

The government has just picked a group of companies and a team of researchers tasked with turning the ambitious, multi-billion-dollar dream of unlimited clean energy into reality in coming decades.

With few energy resources of its own and heavily reliant on oil imports, Japan has long been a leader in solar and other renewable energies and this year set ambitious greenhouse gas reduction targets.

But Japan's boldest plan to date is the Space Solar Power System (SSPS), in which arrays of photovoltaic dishes several square kilometres (square miles) in size would hover in geostationary orbit outside the Earth's atmosphere.

"Since solar power is a clean and inexhaustible energy source, we believe that this system will be able to help solve the problems of energy shortage and global warming," researchers at Mitsubishi Heavy Industries, one of the project participants, wrote in a report.