On Earth, harvesting solar energy is limited to daylight hours, and is affected by weather conditions and the seasons of the year. But in space, those constraints don't apply, and space-based solar power could provide a continuous supply of clean, renewable energy, regardless of the time of year or any inclement weather on Earth.
In an effort to increase the options for supplying Japan with energy, their space agency, JAXA, is developing a method of harvesting solar energy from geostationary satellites sitting 36,000 km above the Earth, and transmitting it down to the planet's surface in the form of either laser beams or microwaves. The agency aims to launch a successful space-based solar power system by 2030, and is currently conducting ground-based experiments to determine the most effective way to transmit the energy across large distances.
"There are many technological challenges to solve before SSPS can be implemented. However, in principle, we are getting close to the stage where it is feasible, and we have just moved from the study phase to the technology demonstration phase. Researchers have started preparation for the world's first demonstration of 1kW-class wireless power transmission technology, and are aiming for practical use in the 2030s." - Yasuyuki Fukumuro, JAXA
Sending energy across tens of thousands of miles without huge losses and without endangering any life on Earth does present significant challenges that would need to be overcome in order to implement a space-based power system. The energy beam would need to travel 36,000 km and hit a receiving stations just 3 km in diameter on the surface of the planet, but Fukumuro, who is in charge of research planning for the Space Solar Power Systems project, believes "Japan currently has the most advanced technology to do this".