At the turn of the last century, there was considerable speculation that meaningful amounts of power might be transmittable wirelessly. Nikolai Tesla conducted extensive experiments, but the constraints of physics frustrated early attempts, particularly the need to generate very short wavelength beams to carry meaningful amounts of power. Today, things are changing. The Defence Advanced Research Projects Agency (DARPA) has announced a high-tech project to transfer power, wirelessly, through the air and possibly through space.
Called the Persistent Optical Wireless Energy Relay, or POWER program, the agency has selected a three-company team to develop hardware, which in a later phase will be mounted on aircraft for tests. The goal of the project is to create a technology which could be used to power drones and eventually aircraft from ground and possibly space-based energy sources. Problems to be overcome include attenuation of the beam from atmospheric effects and conversion losses where relay stations must be used.
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Episode Transcript:
Transmitting signals wirelessly has been a core technology since the turn of the last century. Information has been transmitted multiple ways over the air, from simply turning the carrier wave on and off using Morse code, to modulating the carrier wave with amplitude or frequency modulation, or by transmitting binary high and low states for modern digital communication.
In every case, however, the amount of power transmitted is low. What if it was possible to transmit useful amounts of power without wires, over the air?
The U.S. Defence Advanced Research Projects Agency (DARPA) is exploring the possibility with their Persistent Optical Wireless Energy Relay, or POWER program. The program aims to demonstrate the essential components needed for a truly wireless speed-of-light energy distribution network.
If successful, the ability to transmit meaningful amounts of power without wires could have global implications, unlocking diverse and remote energy sources, including those from the Earth’s orbit or beyond.
The agency has selected three teams—RTX Corporation, Draper and BEAM Corporation—to design and develop optical power relays. The first phase of the project will develop the enabling technology, which in the second phase will be carried by pods on aircraft. The final phase of the project intends to demonstrate an airborne optical power transmission system that can deliver 10 kW of energy to a ground receiver 200 km away from a remote ground source laser.
The military applications include very long duration drone operations without the need to carry large amounts of onboard fuel or air-to-air refuelling.
The technical challenges are considerable, from signal attenuation due to atmospheric effects, to the conversion losses that are inevitable when waves are converted to current and back again through relays. Orbital or very high-altitude systems may alleviate many of these problems.
The first phase is expected to last 20 months, with an optional three-month extension, if necessary, while the second phase will involve an open tendering process in early 2025, focused on integration of the relay technologies into an aircraft.
The future of drones, and possibly passenger carrying aircraft, may involve electric power beamed to the airframe from the ground, or even space.