Space Based Solar Power Lights Up Japan's Energy Future

An ambitious long-term program by JAXA, Japan's space agency, seeks to set up a reliable and environmentally friendly solar energy collection system thousands of miles above the Earth.

Solar power has always had its drawbacks as an alternative energy source. What happens on cloudy days, or for that matter, during the night? How much does accumulated dust on the solar panels reduce their efficiency? And of course, who can protect isolated solar power collection stations from theft, vandalism or terrorism? Most of these questions will be rendered moot if the collection infrastructure is lofted into earth orbit!

Not just any orbit, mind you. JAXA plans on launching its solar collection satellites into geosynchronous orbit 36,000 kilometers (about 22,500 miles) up. At that distance, they will rotate the planet at the same speed as Earth's rotational speed - effectively staying in the same location above Japan. The one drawback of geosynchronous orbit is that a satellite will be plunged into darkness during Japan's evening hours, being blocked from the sun's rays by the width of the Earth. 

Sunlight collected by the orbiting satellite(s) will not merely be reflected to the ground in the fashion of a mirror. Instead, the energy will be converted into microwaves and "beamed" down to ground-based receiving stations that will then convert the microwave radiation into electricity.

Projections by JAXA anticipate each gigawatt power station providing power to a half-million homes. JAXA's detailed plans anticipate having a working Space Solar Power System, or SSPS for short, in operation by the year 2030. (via Pink Tentacle and JAXA)    
Steve Levenstein     
Japanese Innovations Writer     

Jul 12, 2008
by Anonymous

Not blocked in GEO

Power sats in GEO are eclipsed for up to an hour around midnight for a few days around the equinox.

I think they have been talking about lower orbits where there is this problem.

Steve, if you have contacts in Japan, please get in touch.


Keith Henson