In 2025, Japan plans to test the technology of transmitting solar energy from space to Earth

A new global race is underway as countries and organizations vie to develop the technology for transmitting solar power collected in space to Earth. A Japanese public-private partnership has set its sights on conducting a trial around fiscal 2025, intensifying efforts to harness the potential of space-based solar power.

The concept of space-based solar power was initially proposed by an American physicist in 1968. The idea involves launching solar panels into space to generate electricity at an altitude of 36,000 kilometers. Once in space, the solar power is converted into microwaves, which are then transmitted to ground-based receiving stations. These stations convert the microwaves back into electrical energy for use on Earth.

One of the leaders in this field is a group in Japan chaired by former Kyoto University President Hiroshi Matsumoto. This group has been at the forefront of research on space-based solar power and made significant advancements in the 1980s when it successfully transmitted power via microwaves in space. Continuing the research, the group achieved a milestone in 2009 by using an airship to transmit power from an altitude of 30 meters to a mobile phone on the ground. The team is now dedicated to refining the core technology required for wireless power transmission.

In 2009, an industry-government-academia project was launched under the leadership of the Ministry of Economy, Trade and Industry, with Kyoto University professor Naoki Shinohara heading the technology committee. The project achieved successful microwave power transmission experiments horizontally in 2015 and vertically in 2018, both over a distance of 50 meters. The team aims to push the boundaries further by attempting vertical transmission over distances ranging from 1 km to 5 km in future experiments.

Looking ahead, Shinohara envisions the demonstration of their technology as a bargaining tool for space development collaborations with other countries. He believes that being at the forefront of this global race will provide Japan with an advantageous position in negotiating future endeavors in space.

In pursuit of commercialization, other competitors have also emerged. The U.S. Air Force Research Laboratory and the California Institute of Technology are each pursuing large-scale space-based solar power projects. Additionally, institutions such as Chongqing University in China and the European Space Agency are actively developing their own technologies and plans in this area.

The renewed interest in space-based solar power can be traced back to energy crises throughout history. NASA and the U.S. Department of Energy initially explored the concept during the oil shock decade of the 1970s. However, as the urgency of the crisis waned, the idea lost momentum. It was not until around 2000, with the advent