Japan planning $21bn solar power station in space

Japan is developing a giant solar power space generator that it expects to begin transmitting solar energy to earth from an orbit 36,000km above the earth's within the next 30 years.

The $21bn (£13bn) government-backed project includes plans for the construction of a solar space station comprising four square kilometres of solar panels with a total capacity of 1GW – enough to supply about 294,000 homes in Tokyo, according to a statement posted yesterday on the Ministry of Economy, Trade and Industry web site.

Over the next four years, the project will focus on developing technology that will send the electricity generated by the orbiting solar panels back to Earth in the form of microwaves.

In 2015, the government plans to launch a small satellite fitted with solar panels, which will be used to test the effectiveness with which the technology can beam electricity from space through the ionosphere – the outermost layer of Earth’s atmosphere. The station is expected to be fully operational in the 2030s.

"It sounds like a science fiction cartoon, but solar power generation in space may be a significant alternative energy source in the century ahead as fossil fuel disappears," Kensuke Kanekiyo, managing director of government think-tank Institute of Energy Economics, told the Bloomberg news agency.

The project is being led by the trade ministry and the Japan Aerospace Exploration Agency, with participation by a research group representing 16 businesses. They include Japanese thin-film photovoltaic module producer Mitsubishi Heavy Industries, its solar cell and satellite-making sister company Mitsubishi Electric Corp, and Tokyo-based IHI Corp, which produces space development-related equipment.

Transporting panels to the planned solar station will be prohibitively expensive, so Japan needs to find a way to reduce costs to make it commercially viable, Hiroshi Yoshida, chief executive of Excalibur, a Tokyo-based space and defense policy consultancy, told Bloomberg.

"These expenses need to be lowered to a hundredth of current estimates," he warned.

However, advocates of space solar projects point out that solar energy at the edge of the Earth's atmosphere is estimated to be 10 times greater than on the surface, as there is no atmospheric or cloud interference. Much of the technology required to transmit the energy to Earth is also based on existing satellite systems.

The Japanese project mirrors a similar US initiative that earlier this year saw energy giant PG&E announce that it would purchase power provided by California-based space solar firm Solaren Corp, which is aiming to start beaming solar power from outer space within seven years.