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The Defense Advanced Research Projects Agency (DARPA) reported that a project team testing a new optical wireless power receiver technology was able to transfer 800 W of power to a receiver located 8.6 km away in a 30-second transmission. It claims this is a distance and power record among optical power transmission demonstration results. The U.S. Defense Advanced Research Projects Agency (DARPA) announced record results in a test campaign of a new optical power transmission receiver. The team recorded more than 800 watts of power delivered during a 30-second transmission from a laser 8.6 kilometers away, DARPA said. The results represent distance and power records for this type of wireless power transfer among reported demonstrations, according to the researchers. The longest reported distance so far for an appreciable amount of optical power, greater than one microwatt, was 230 watts of average power at 1.7 kilometers for 25 seconds. They also reported a power transfer of 3.7 kilometers for an undisclosed amount. Theres no question that we absolutely blew away all previously reported optical power transmission demonstrations in terms of power and distance, said Paul Jaffe of DARPAs Tactical Technology Office in a statement. Describing how the new optical power transmission receiver works, DARPA explained that the laser beam enters an aperture, strikes a parabolic mirror, and reflects off dozens of photovoltaic cells arranged around the interior of the device, which convert the energy back into usable power. No further technical details about the emitter, transmitter, or laser technologies were disclosed. Both the optical transmitter and receiver were on the ground during the experiments. Its much easier to send an energy beam directly up or down relative to the ground because theres much less atmosphere to pass through, Jaffe said. The work was completed as part of DARPAs Persistent Optical Wireless Energy Relay (POWER) program, a multi-phase initiative that envisions a network of optical transmitters and receivers acting as a relay system to instantly transmit power from a location where it can be easily generated to where its needed. For example, powering devices in remote and hazardous locations where fuel delivery capabilities are limited, such as battlefields and disaster zones. Although the focus of the demonstration was to rapidly validate a new designs ability to extend potential distance rather than efficiency, the team reported that at shorter distances the receiver achieved 20% efficiency. During the test campaign, more than one megajoule of energy was transferred, it added. The receiver, which reportedly has the potential to be scaled for use with unmanned aerial vehicles (UAVs), was designed by Teravec Technologies, with support from Packet Digital and the Rochester Institute of Technology, all based in the US. The research group also included scientists from the U.S. Naval Research Laboratory and the U.S. Army High Energy Laser Systems Test Facility. Looking ahead, the next phase of the POWER program, which is open to new potential research partners, will demonstrate the benefits of integrated relays and vertical power transmission. Several groups are developing power transmission technology. Two recent ones applying it in a space or satellite context are Space Solar in the United Kingdom and Aetherfulx in the United States. |
