Japanese version is here.
Today, radio waves are mainly used for transmitting intelligence and information. However, the threat of the lack of energy resources, especially for electrical energy, is increasing as a result of the population explosion and rapid industrialization over the globe. Therefore, considering that the energy problem on our mother planet Earth, and the crisis of the Earth's environment have become urgent issues for mankind, we need to re-examine the use of radio waves for transmission of clean electrical energy from one place to another, especially from space to the ground, without wires. The idea of radio power transmission was first conceived by Tesla about a century ago . However, the first practical use of radio waves was for transmitting intelligence and information, and not for transmitting electrical power per se.