The Japan Aerospace Exploration Agency (JAXA) that their scientists have successfully transmitted 1.8 kilowatts of power wirelessly to a receiver 170 feet away.
The distance isn’t large but it is a small proof of concept that will be essential if the agency’s Space Solar Power Systems (SSPS) program is ever going to be a reality.
“This was the first time anyone has managed to send a high output of nearly two kilowatts of electric power via microwaves to a small target, using a delicate directivity control device,” a spokesman for the agency told AFP.
The idea behind JAXA’s SSPS program is to have microwave emitting solar panels in a geosynchronous orbit, 22,300 miles from Earth.
The idea behind space based solar power was originally introduced, fictionally, by Isaac Asimov in 1941 in the short story Reason. As a non-fiction concept it was originally described in 1968 and patented by American aerospace engineer Peter Glaser in 1968.
Starting in 1978 the U.S. Department of Energy (DOE) and NASA explored the technology under the Satellite Power System Concept Development and Evaluation Program. Given the prohibitive cost of the program however, it was cancelled by Ronald Reagan in 1986.
Since that time, Japan has been the only country to seriously pursue the idea. According to statements by JAXA’s Yakuyuki Fukumuro “.. in Japan, probably reflecting our nation’s shortage of energy resources, SSPS research was started early, and has since been pursued by many universities and JAXA.”
Even after years of research, however, Japan still has a long way to go.
“When transmitting power by microwaves, a significant technological challenge is how to control the direction, and transmit it with pinpoint accuracy from a geostationary orbit to a receiving site on the ground. Transmitting microwaves from an altitude of 36,000 kilometers to a flat surface 3 km in diameter is like threading a needle. In my opinion, Japan currently has the most advanced technology to do this,” said Fukumuro.
Solar power from space obviously has many advantages. In space, without the interference of the Earth’s atmosphere, weather, and magnetic field the solar panels could receive sunlight 99 percent of the time and function at about 144% of the maximum attainable solar intensity available anywhere on Earth.
Because the planned receiving platform is at sea, it would also take up no significant real estate which could be put to other purposes.
The concept is especially appealing in Japan. Currently the country receives most of it’s energy from fossil fuels and nuclear plants, which have become increasingly unpopular in the wake of the 2011 Fukushima disaster.
“Although, Japan depends on imported energy resources today, if we can establish SSPS technology, it may even become possible for us to become an energy exporter. We would like to continue to lead the world in SSPS technology development, so that Japan will be able to play a major role as a contributor to the world’s energy supply,” said Fukumuro.
An overview of the SSPS design being explored by JAXA can be found in an April, 2014 article at IEEE Spectrum.
In addition to technological questions there are concerns over both cost and safety to be addressed. Many are uncomfortable with the idea of beaming high energy microwaves to Earth. The technology would have to be adapted to a point where the orbiting solar panels never missed their target. It is also unclear what effect events such as solar storms might have on the transmission of energy.
It is also likely that, if the technology ever reaches the point of feasibility, that the country will have to find international partners before it can be implemented.
Building the massive solar array in space could be as large a project as the International Space Station. That project began construction in 1998 and still sees regular repairs, burgess and expansions today. It also involved the cooperation of the United States, the Russian Federation, Canada, Japan and 11 members of the European Union.
According to a Jaxa Spokesperson “it could take decades before we see practical application of the technology—maybe in the 2040s or later.”