The U.S. Defense Advanced Research Projects Agency (DARPA) has announced a new Persistent Optical Wireless Energy Relay (POWER) program that plans to use lasers relayed from airborne platforms to power machines thousands of miles away, which sounds like the wildest science fiction.
There are many potentially brilliant technologies that could change the world, but there is one fundamental limitation - how to power them. This is especially true for airplanes. Electric planes sound like a great idea, but the batteries needed to power them are bulky, taking up valuable payload and range.
For more than a century, the idea of transmitting electricity through wireless broadcasts seemed like the obvious solution, but issues such as fundamental physical laws have stymied the idea. Now, the U.S. Defense Advanced Research Projects Agency (DARPA) is investigating using lasers to transmit power from a ground source to a distant receiver, providing virtually unlimited range for things like electric aircraft.
In theory, this seems simple, but there are various technical issues to overcome. Lasers operate along line of sight, so onboard repeaters are required in the upper atmosphere to minimize distortion and attenuation caused by air and water vapor. Additionally, like laser weapons, transmitters and repeaters need to be able to lock on to the target and correct the beam to maintain focus.
However, the biggest problem is that the laser beam will generate a lot of losses during multiple jumps. According to DARPA, POWER is currently in its first phase of developing a conceptual design for the repeater. The second phase will focus on integrating the technology into existing airframes, while the third phase will see testing delivering 10 kilowatts of laser power over a range of 200 kilometers (125 miles).
Dr. Paul Jaffe, leader of the DARPAPOWER project, said: "This project has the potential to increase the speed of power transmission by several orders of magnitude, thereby fundamentally reshaping society's relationship with energy. Wireless energy networks can be obtained from a variety of new energy sources, including space. power and connect them to energy-poor consumers quickly and reliably."
"Energy is the foundation of all human activities, including defense. We need energy delivery methods that overcome the fragility and other shortcomings of existing models. The next leap in optical power transmission may depend on relay technology."