In a quest for the world’s first demonstration of space-based solar power, Japanese researchers are resolutely marching forward with a target set for 2025. This ambitious undertaking spearheads several decades of persistent research efforts in which Japan has been a global frontrunner. The project involves a unique collaboration between the Japan Aerospace Exploration Agency (JAXA) and a private entity, setting their sights on the harnessing and beaming of solar power from space.
The conception of space-based solar power dates back to 1968, when it was first proposed by Czech-born NASA engineer Peter Glaser. In the 1970s, during the oil shock decade precipitated by geopolitical tensions, NASA and the U.S. Department of Energy took a keen interest in the idea. However, once the crisis ebbed, the concept lay dormant for over twenty years until the Kyoto Protocol spurred interest anew as a solution to escalating emissions. This was the juncture at which JAXA stepped into the picture, dedicating its research and resources to bring this vision into reality.
The theoretical basis of space-based solar power involves using microwaves to transmit solar energy back to Earth, as microwaves are unaffected by cloud cover and thus provide a consistent means of energy transportation. The received energy is then converted into electricity at ground stations. Japan, as an innovator in this domain since the 1980s, made significant strides when its researchers successfully achieved power transmission using microwaves in space.
In 2009, a groundbreaking experiment was carried out under the leadership of Professor Naoki Shinohara at Kyoto University, demonstrating power transmission from an altitude of nearly 100 feet to a mobile phone on the ground. Since then, the team has further honed its technology, making notable advances in horizontal and vertical microwave power transmissions, albeit over limited distances.
Shinohara is confident that Japan’s early demonstration of this technology will give the nation an advantageous position in the international space research community. The 2025 experimental plan includes the use of small satellites beaming microwaves to ground stations hundreds of miles away. This will place Japan in direct competition with entities like the U.S. Air Force Research Laboratory, the California Institute of Technology, the European Space Agency, and China’s Chongqing University, all of whom are in the race to develop similar technologies.
Despite the excitement around the prospective demonstrations, the feasibility of commercial applications remains a formidable challenge. Current solar technologies would necessitate a one-gigawatt space solar plant, equivalent to a nuclear reactor, to extend solar panels over a staggering area of 1.25 miles in both length and breadth. Such an endeavor comes with an astronomical price tag exceeding a trillion yen (more than US$7 billion), casting a shadow of uncertainty over the commercial future of space-based solar power. However, the world eagerly awaits the outcomes of these Japanese trials as they could potentially reshape the future landscape of renewable energy.
