Japanese researchers want to demonstrate space-based solar power by 2025

The country has led the research effort for many decades and now wants to be the first to achieve the goal.
Ameya Paleja
Small satellites in space could beam back solar power to Earth
Small satellites in space could beam back solar power to Earth


A partnership between a private entity and Japan Aerospace Exploration Agency (JAXA) is working toward beaming solar power from space. If all goes well, the partnership could run its first trial as early as 2025, just a couple of years from now, Japanese media outlet Nikkei reported.

Space-based solar power was first suggested by Czech-born NASA engineer Peter Glaser in 1968. Geopolitical conditions just a couple of years later led to the oil shock decade of the 1970s, when the idea received support from NASA and the U.S. Department of Energy.

However, with the crisis over, the concept took a back seat for more than two decades, when it was revived again to tackle increasing emissions after the Kyoto Protocol. This was when JAXA got involved in the research and has been pushing hard to turn it into reality.

Japanese Contribution to space-based solar Power

To beam back solar energy generated in space, scientists plan to use microwaves, the same waves that cook our food in microwave ovens. Since microwaves are undeterred by cloud cover, they are the ideal means to transfer solar power back to the receiving stations on the ground, where they can be converted into electrical energy.

Japan has been a world leader in this space since the 1980s when researchers achieved power transmission using microwaves in space. In 2009, a research group led by Naoki Shinohara, a professor at Kyoto University, transmitted power from an altitude of nearly 100 feet (30 m) to a mobile phone on the ground.

Japanese researchers want to demonstrate space-based solar power by 2025
Large solar farms could be a thing of the past.

Over the years, the team has worked to refine its technology and demonstrated microwave power transmissions both horizontally and vertically. Conducted in 2015 and 2018, these transmissions only transferred power up to a distance of a little over 160 feet (50 meters). In the future, the researchers aim to carry out these transmissions over distances ranging from 1,000 yards (1 kilometer) to over 3 miles (5 kilometers).

Shinohara believes that if Japan can demonstrate this technology before the rest of the world, it will offer the country a bargaining tool with other nations engaged in space research.

As part of its plans to demonstrate the working of the technology, the team plans to use small satellites which will beam microwaves to ground stations hundreds of miles away. The experiment will be attempted in the year 2025 when Japan hopes to beat the likes of the U.S. Air Force Research Laboratory and the California Institute of Technology in the U.S., the European Space Agency, and Chongqing University in China, who are also racing to develop similar technologies.

Demonstrations aside, the commercial application of the technology is still a major challenge. With currently available solar technologies, a one-gigawatt solar plant in space, the equivalent of a nuclear reactor, would require panels that extend for 1.25 miles (2 kilometers) for their length and breadth. This is estimated to cost more than a trillion yen (>US$7 billion).

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