Military looks forward to a future era when power can flow by airborne relay to forces in the field
THE MIL & AERO BLOG – Imagine a future era when military forces on the ground, at sea, and in the air could harvest electrical power as needed from high-altitude crewed and uncrewed aircraft operating in the theater as far away as 125 miles.
That's exactly what researchers from the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., are envisioning with the POWER Receiver Array Demonstration (PRAD).
PRAD seeks to blend electro-optical and electrical technologies to distribute as much as 10 kilowatts of electrical power to military uses over laser beams from military aircraft or unmanned aerial vehicles overhead.
PRAD seeks to demonstrate enabling technologies in power beaming, as part of the DARPA Persistent Optical Wireless Energy Relay (POWER) project. POWER seeks to demonstrate optical power-beaming relays not only as a resilient multipath alternative for expeditionary energy transport, but also to enable small-yet-persistent manned and unmanned aircraft to provide on-demand power for a wide range of military missions.
If the military can develop power-beaming lasers that operate from manned and unmanned aircraft, how long will it be before on-demand power can come from low-Earth-orbit satellites? Probably not long at all, after the technology is developed.
POWER optical technologies are expected to create an airborne relay capable of redirection, wavefront correction, and energy harvesting of optical beams. The ultimate goal is to use three airborne relay nodes hosted on existing aircraft to transmit energy from a ground source laser to 60,000 feet in altitude, and back down to a ground receiver 125 miles away.
The PRAD program seeks to develop and demonstrate a laser power beaming receiver for a future energy web that consists of three major component types: transmitters, relays, and receivers.
Optical laser power beaming delivers energy over long distances via transmission by laser beam that is then directed towards a receiving station. The receiving station is equipped with photovoltaic cells or similar devices that capture the laser energy and convert it back into electrical power.
A ground-to-ground demonstration is crucial for proving the feasibility and effectiveness of optical laser power beaming -- particularly in validating the photovoltaic receiver array and its efficiency, DARPA researchers explain.
The RTX Raytheon segment won a $10 million contract in August 2023 for the DARPA POWER project. The next step is to develop and demonstrate a laser power beaming receiver for the POWER program.
POWER seeks balance energy generation, storage, and distribution for military missions by capitalizing on power beaming for near- instantaneous energy transport.
Military power today relies primarily on liquid fuels like jet fuel, gasoline, and diesel fuel, which are vulnerable to enemy attack and require significant infrastructure. Instead, POWER seeks to reduce the military's dependence on liquid fossil fuels, their delivery, and storage capacity.
Speed-of-light energy transport through a multipath network would enable rapid reconstitution under attack, graceful degradation, and resilience by re-routing energy through the network in a matter of seconds or minutes, and restoring full capability by replacing nodes in minutes or hours.
For the POWER program, Raytheon seeks to deliver 10 kilowatts of laser energy to the final ground node using a 50-kilowatt source laser, transmitted through three airborne relay nodes using system apertures smaller than one meter diameter.
In POWER's first phase, Raytheon is developing a relay payload design and relay platform. The PRAD part of the POWER program seeks to build a low-power demonstration relay.
Eventually DARPA would like to demonstrate three airborne nodes relaying power to a ground receiver at White Sands Missile Range, N.M., using the High Energy Laser Systems Test Facility (HELSTF), and the RQ-4 Global Hawk large unmanned aircraft as an airborne relay.
Companies interested were asked to email 3-page abstracts in September to [email protected]. Email questions or concerns to DARPA at [email protected]. More information is online at https://sam.gov/opp/51e880f298304099a8b2f62352617a2f/view.
John Keller | Editor-in-Chief
John Keller is the Editor-in-Chief, Military & Aerospace Electronics Magazine--provides extensive coverage and analysis of enabling electronics and optoelectronic technologies in military, space and commercial aviation applications. John has been a member of the Military & Aerospace Electronics staff since 1989 and chief editor since 1995.
