DARPA has tapped Raytheon to design and develop a wireless, airborne relay system to "deliver energy into contested environments," as part of its Energy Web Dominance program, in which DARPA wants to be able to power anything from nearly anywhere.
Under a two-year, US$10 million DARPA contract, Raytheon will create a Persistent Optical Wireless Energy Relay (POWER) system, using a series of high altitude unmanned aircraft equipped with laser-based power receiving and transmitting capabilities. Energy will be beamed up to high altitude, then relayed across however many jumps are necessary to reach the target area.
That target might be on the ground, or it might itself be another autonomous aerial platform, in which case it could stay airborne as long as necessary, its batteries being constantly charged from afar.
With enough of these power-relaying birds in the air, the POWER system creates an "energy web" that military logisticians can use to route energy where it's most needed at a moment's notice. It's a supply line in the sky, capable of giving land, sky or sea-based robots indefinite endurance, or sending the same energy elsewhere if it's strategically necessary.
"This is the internet for energy, harnessing resilient, multipath networks to flow energy from abundant sources to energy-starved consumers," said Col Paul Calhoun, POWER program manager in DARPA’s Tactical Technology Office. "The military faces particularly acute energy challenges, which are driving this innovation. We often must operate far from established energy infrastructure and rely on liquid fuels that require precarious supply lines."
There is of course a drawback, and in this case it's the fact that you're throwing a fair amount of energy away to gain that flexibility. You lose some – maybe around 20% – when you convert electricity to light in your laser. You lose more – maybe 50% – when you convert that laser back to electricity at the receiver. And in this kind of relay station set up, you'd lose that power at every step of the way.
Mind you, plenty of energy is already spent moving fuel around, from refineries to tankers to trucks – and this kind of airborne supply line would eliminate the personnel risk normally involved with moving energy around in a war zone. And you can beam this power over from a spot where it's easy and convenient for you to produce it in bulk – potentially even just grabbing it straight out of the nearest power grid – so efficiency is probably well down the list of priorities.
DARPA seems bullish on the technology, not just for military purposes, but for distributed power in civilian life as well. "We believe the next energy revolution will be enabled by the wireless energy web," said Calhoun. "It will dramatically compress transport timelines and resiliently provide distributed energy to consumers in air, on land, on the sea, undersea, and in space."
Source: Raytheon