DARPA Wants to Power Distant Military Bases with Laser-Beaming Drones

“This is the internet for energy.”

Pictured above: U.S. Marines inspect a Tactical Unmanned Aerial System RQ-7B Shadow. The Shadow drone is capable of providing reconnaissance, surveillance, and a laser designator for air support. Pohakuloa Training Area, Hawaii, 2015.

Lance Cpl. Robert D. Williams Jr., Public domain, via Wikimedia Commons

Future U.S. military outposts may no longer rely on convoys delivering diesel fuel for electrical power, but instead a system of drones wirelessly beaming it across the sky.

The Defense Advanced Research Projects Agency’s (DARPA) new Persistent Optical Wireless Energy Relay (POWER) initiative would use lasers to beam electricity across military theaters, saving lives by reducing the number of military convoys required to keep forward bases running. While the system would likely run into the same issues affecting other lasers, it would be a huge advantage for the Pentagon’s expeditionary forces worldwide.

The POWER program will design and implement what the agency calls “airborne optical energy relays.” Uncrewed drones will loiter at altitude, equipped with relays capable of passing on high-powered laser beams.

DARPA’s rendition of the prototype POWER drone.

The system would work like this: a military power station, possibly even nuclear powered, would generate electricity and then turn it into a coherent laser beam. The beam would be aimed at a relay drone, which would in turn beam it farther down the line to another drone. Finally, the last drone would aim it at a military base or outpost where the laser would be converted back into electricity.

“This is the internet for energy,” says Colonel Paul Calhoun, DARPA’s POWER program manager, in the announcement.

In 2009, Wired reported that the U.S. war in Afghanistan used an average of 22 gallons of diesel fuel per soldier each day. In addition to the market price, fuel costs $45 a gallon to haul to the battlefield. “Fuel,” Wired reported, “has to be driven into Afghanistan’s isolated bases. Which opens up U.S. convoy to improvised bomb attacks. Which invariably leads to troops dying.”

A DARPA diagram depicting how drones would use lasers to transmit energy.

A straightforward way of sending electrical power to a military outpost would have several advantages. It would reduce the amount of fuel needed to be trucked to remote bases, removing the cost of transport fees and the risk to drivers. It would remove the need for generators to convert diesel fuel into electricity, eliminating the need for generator maintenance and, as a quality of life issue, the constant smell of diesel exhaust.


Such a system would not eliminate the need for all diesel fuel, at least for now. Most U.S. military vehicles, including the replacement for the 1980s-era Humvee, the Joint Light Tactical Vehicle, would still require real diesel fuel. Future vehicles, built with hybrid engines, could require more electricity and less fuel, or even cease using fuel entirely.


Laser-based power transmission would come with some issues inherent to lasers, though. A truck transferring 1,000 gallons of diesel will arrive at its destination with 1,000 gallons of diesel. Lasers, on the other hand, lose coherency over distance, so some loss of energy would be expected. The problem grows worse as the laser passes through smoke, dust, or water particulates. Drone relays would have to stay one step ahead of the weather, avoiding clouds and bad weather. If weather or other issues shut down transmission entirely, on-site battery storage could provide power until it passes.

A Pakistani paramilitary soldier stands beside a burning oil tanker following a bomb explosion in the Afghan border town of Chaman, January 14, 2007. A bomb exploded in a tanker carrying oil from Pakistan to U.S. forces in Afghanistan, on January 14, but caused no casualties.

DARPA believes the biggest challenge is in the conversion process, from electricity to laser and back again as the power hops between drones. “In a multi-hop network, converting from a propagating wave back to electricity and back to propagating wave at each node quickly accrues unacceptable losses. Each one of those conversions is relatively inefficient, and multiplying them across a chain is impractical,” the announcement explains.


The solution, Calhoun says, “is efficient power beaming relays that redirect optical energy transmissions while maximizing beam quality at each point along the way.”


As armies turn to lasers, high-powered microwaves, and other directed-energy weapons, supplying those in the field with electricity will become more important than ever. If successful, DARPA would enable the U.S. military to turn fuel-laden trucks into photons moving at the speed of light, fulfilling a base’s energy needs faster and without endangering troops.

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