DARPA Just Set A New Record For Sending Power Wirelessly

In a major step toward replacing traditional power lines with laser beams, DARPA’s Persistent Optical Wireless Energy Relay (POWER) program has achieved record-breaking results in wireless energy transmission. The technology can transform the way power is delivered to military and humanitarian missions where normal supply chains are unworkable or hazardous.

Historically, transporting power—especially across the “last mile”—has been a logistical nightmare. Slinging wires or pipelines cannot be done in rugged terrain or in a hostile area, and troops are then left to carry the fuel by hand. The POWER program DARPA is developing seeks to remove this burden by developing transmission lines of light that would deliver energy with the same ease that Wi-Fi delivers data.

Recent tests in New Mexico are a significant breakthrough. DARPA has managed to beam 800 watts of laser energy over a range of 5.3 miles (8.6 km) in 30 seconds, which is a huge improvement to its earlier record of 230 watts over one mile.

At the heart of this achievement is the Power Receiver Array Demo (PRAD), a spherical object with a small aperture. A parabolic mirror scatters incoming laser light onto an array of photovoltaic cells, which convert the light back into usable electricity. The conversion efficiency is 20 percent currently, but DARPA predicts an increase as the technology develops.

Currently, the emitter and receiver are both terrestrial, but the ultimate goal is to put the relay stations on high-altitude drones. Such airborne relays would minimize the losses in the atmosphere and avoid such obstacles as buildings or terrain.

DARPA is in Phase One of a three-phase development roadmap, with the current efforts being aimed at refining the accuracy of the beam, improving the efficiency, and making the system throttleable. At Phase Three, the aim is to transmit 10 kilowatts of power 125 miles (200 km) through aircraft relays.

Said POWER Program Manager Paul Jaffe, “This demonstration shattered myths about the boundaries of power beaming technology, and it is already causing industry to rethink what can be done.”