In the largest demonstration of power beams in nearly 50 years, a team of researchers from the US Naval Research Laboratory (NRL) recently demonstrated the feasibility of the terrestrial microwave power beam by transmitting 1.6 kilowatts (kW) of power over 1 kilometer to the US Army. Research field at Blossom Point, Maryland.
Called Safe and CONtinuous Power beaming – Microwave (SCOPE-M), the project was funded by the Operational Power Capability Enhancement Fund of the Office of the Under Secretary of Defense for Research and Engineering. SCOPE-M consists of tens of thousands of X-band antennas. Each of these antennas is connected to a small rectifier diode which converts the incident microwave power into direct current electricity.
The NRL team led by Advanced Concepts Group Leader Christopher Rodenbeck established the practicality of the terrestrial microwave power beam and transmitted 1 kW of electrical power over a distance of 1 km using a 10 gigahertz (GHz) microwave beam. SCOPE-M demonstrated the power beam at two locations. The first was at the US Army research field at Blossom Point in Maryland, and the second was at the Haystack Ultrawideband Satellite Imaging Radar (HUSIR) transmitter at the Massachusetts Institute of Technology (MIT) in Massachusetts.
The 10 GHz frequency was chosen because it was able to radiate even in heavy rain with less than 5% power loss, and also, it is safe for birds, animals and humans. In the Maryland tests, the team exceeded their goal by 60% by delivering 1.6kW for just over 1km. The team didn’t have the same peak power at the Massachusetts site, but the average power was much higher, providing more power.
SCOPE-M technology demonstrations pave the way “for power radiation on Earth, in space and from space to Earth using power densities within safe limits set by international standards bodies “. Rodenbeck said power transmission is the ultimate green technology. Unlike other clean energy sources, energy transmitted from space to Earth can supply electricity continuously, 24 hours a day, 7 days a week, 365 days a year.
“Although SCOPE-M was a terrestrial power beam link, it was a good proof of concept for a space power beam link”, said Brian Tierney, Ph.D., SCOPE-M electronics engineer. “The primary benefit of space-to-earth power radiation for the DOD is to alleviate dependence on troop fuel supplies, which may be vulnerable to attack.”