Japan to Test Beaming Solar Power From Space in 2025: Report

In this image taken from NASA video, a solar panel is unfolded at the International Space Station on June 20 2021. (NASA via AP)

Japan is exploring ways to beam solar power from space, a project that’s expected to be tested in 2025, even as concerns remain about the costs involved in such a project.

“If we can demonstrate our technology ahead of the rest of the world, it will also be a bargaining tool for space development with other countries,” Naoki Shinohara, a professor at Kyoto University, told Nikkei Asia.

In about fiscal year 2025, a Shinohara-led group intends to see if power can be transmitted from space to the ground using small satellites.

Space-based solar power would involve placing solar panels at an altitude of 36,000 kilometers (22,369 miles). The solar energy that’s soaked up would be converted to microwaves and transmitted to receiving stations on Earth for conversion to electrical energy. The Japanese Ministry of Economy, Trade, and Industry is at the forefront of harnessing space-based solar power.

In 2015, the group successfully ran microwave transmission experiments horizontally, before attempting vertical transmission in 2018; both experiments were conducted over 50 meters. The team plans to carry out vertical experiments from 1 kilometer (0.62 miles) to 5 kilometers (3.10 miles) in the future.

Cost challenges remain a big question for space-based solar power projects. To generate about 1 gigawatt of power through this method requires solar panels equivalent to the area of a square measuring 2 kilometers (1.24 miles) on each side, an endeavor estimated to cost roughly $7 billion.

Pros and Cons

Space-based solar power has two massive benefits compared to setting up traditional solar panels on Earth. For one, vast areas of land won’t be wasted by covering it with solar panels.

Secondly, while Earth-based solar energy production can be affected by weather conditions, microwaves can pass through clouds, which would make for a stable supply of beamed-down power regardless of the time of day and weather.

The process of converting electricity into microwaves in space and then converting these microwaves into electricity at an Earth-based facility is said to be inefficient.

The solar cells in space would also be under constant bombardment by micrometeorites, thus risking significant damage. By the end life of these cells, their disposal, which would potentially litter space with more debris, raises concerns.

Other Projects

Japan isn’t the only nation pursuing space-based solar power projects. In July 2022, the UK government announced funding for such initiatives after an engineering study concluded that the technology was viable.

In the United States, a project called the Space Solar Power Incremental Demonstrations and Research (SSPIDR) is being conducted by the Air Force Research Laboratory that’s exploring critical technologies required for space-based solar power.

China is looking at space-based solar power as well, with a state-funded prototype program established in 2019. Beijing plans to hold a demonstration of a 100-kilowatt system in low Earth orbit in 2025. By 2030, the county intends to set up a space-based solar power station in geostationary Earth orbit at a height of 36,000 kilometers (22,369 miles).

In Europe, the European Commission is funding research activity on space solar reflectors. The project involves using large, lightweight reflectors to redirect sunlight to utility-scale solar power farms on Earth.