Washington (USA) Scientists at the NRL (Naval Research Laboratory), a research facility of the United States Marine Corps and the United States Navy, wirelessly transmitted 1.6 kilowatts of electrical energy over one kilometer to demonstrate the feasibility of terrestrial microwave power beaming. To do this, they converted electricity into microwaves, which were then sent to a receiver in a directed beam. To precisely focus the microwave beam, the researchers used a dish as a transmitting antenna. According to the NRL, this is “the most significant demonstration of power beaming in almost 50 years”.
Microwave power beaming is the point-to-point transfer of electrical energy across free space by a directed microwave beam. The project was funded by the Office of the Undersecretary of Defense for Research and Engineering’s Operational Energy Capability Improvement Fund and is called “Safe and Continuous Power beaming – Microwave (SCOPE-M)”.
The microwave beam is received with a rectifying antenna (rectenna), which consists of a large number of small microwave antennas. These work in the X-Band, the frequency range between 7 and 11.2 gigahertz (GHz). A diode then converts the incoming electromagnetic waves back into DC electrical power. In the demonstration system, the NRL used the 10 GHZ band because the technology is considered to be mature and available at low cost.
Brian Tierney, Ph.D., SCOPE-M electronics engineer, said “Although SCOPE-M was a terrestrial power beaming link, it was a good proof of concept for a space power beaming link (…) The main benefit of space to Earth power beaming for the DOD is to mitigate the reliance on the fuel supply for troops, which can be vulnerable to attack.”
In the future, the US Department of Defense would like to use the technology for wireless power transmission from space. According to plans by the US military, troops deployed abroad are to be supplied with energy via power beaming. They would then be independent of fuel deliveries. China is also working on a similar concept, but it is intended for civilian use.
Christopher Rodenbeck, Ph.D., Head of the Advanced Concepts Group, NRL stated that power beaming is the ultimate green technology. Unlike other clean energy sources, power beamed from space to Earth can provide power continuously 24/7 – 365 days a year.