As drones are increasingly used for a variety of applications, the industry is continuously investing in innovations to expand their functionality. One such aspect is researching the feasibility of powering drones with lasers to enable continuous flight. The possibility of this technology has been known for well over a decade, but so far no one has succeeded in commercialising it. While there are a lot of hurdles and implications to consider, the potential benefits have piqued the interest of companies and researchers across the globe.
Why we need laser-powered drones
Battery power is one of the biggest constraints of drones and UAVs, because it limits the flight duration. To increase the time a drone is able to stay up in the air, bigger batteries are needed, which increases the size and weight of the vehicle. This is less than ideal because it reduces other capabilities such as manoeuvrability and speed. With a variety of drone applications that require long-term flight, like inspection, infrastructure, surveillance and inventory management, there needs to be another solution. Of course, investments have been made in extending battery life which has led to a steady improvement, though still limited. Therefore, companies are looking at alternative means for charging drones in-flight.
One option is utilising tethers to send power continuously and automatically to the drone, like Elistair’s tethered drones. However, this leashes the vehicle to the ground, requiring it to remain stationary. Other companies have developed autonomous smart drone charging systems, such as Hextronics’ battery-swapping solution, Skycharge’s adaptable charging pad and Global Energy Transmission’s wireless power network. Though revolutionary, these solutions require the drone to seize activities to return to the station to charge. So, what if you can power drones in-flight, from a considerable distance? That is where the idea of laser wireless power transmission comes in.
Research and development look promising
One of the first businesses to test out laser power beaming for aircraft propulsion is PowerLight Technologies. This US company was able to demonstrate the technology in 2012 by keeping a quadcopter UAV airborne for 48 hours in a wind tunnel, as well as powering a Lockheed Martin Stalker UAS outdoors from a range of up to 600 meters. To do so, they used infrared semiconductor diode lasers to power a small photovoltaic array attached to the drone. Since then, PowerLight has worked on improving the technology to be long-range, lightweight and compact, including safety shutdown systems and capable of working in any weather conditions.
They also partner with other companies in DARPA’s POWER programme (Persistent Optical Wireless Energy Relay), an initiative of the US military to deliver energy to places that are difficult, expensive or dangerous to reach. Other companies in this programme, such as Raytheon, are working on developing wireless optical power relays, creating an airborne relay design. These ‘energy webs’ would be capable of harvesting, transmitting and redirecting optical beams, which can transmit energy from ground sources to drones at high altitude and long distances.
In China, researchers at the Northwestern Polytechnical University (NPU) in Xianyang have also been working on making laser-beam powered drones a viable technology. They have demonstrated the capability of a remote charging system which they are calling optics-driven drones (ODD). This system converts light energy into electricity by attaching a photoelectric converter to the bottom of the drone to capture the laser’s energy.
To track the drone and keep the beam targeted on its intended destination, they developed intelligent visual tracking algorithm, as well as an adaptive beam shaping system to autonomously adjust the intensity of the beam to increase the distance of wireless transmission. They also designed a protection algorithm to identify obstacles and quickly adjust the power of the laser beam to a safe level. The technology was tested successfully in one indoor and two outdoor field tests, both at night and during the day.
So here’s the deal
Though research shows that laser-powered drones can be viable, there is still a lot to be done to commercialise it. Running a high-energy laser beam 24/7 can be quite expensive and would require massive amounts of energy, especially considering the efficiency of the energy transmission and the degradation of the laser over large distances. Moreover, there are quite a few safety concerns with the potential dangers of using lasers across open spaces.
However, the potential benefits and applications are worth continuing the development of this technology. It is not just useful for military purposes, but also for a variety of commercial and urban applications including disaster relief, traffic control, inspection and remote package delivery. Therefore, it is interesting to keep an eye on companies developing laser-power beaming technology, such as the Luxemburg-based start-up Skygrids, founded by EUROAVIA alumnus Jan Van Baelen.
Even so, only the future will tell whether this technology will ever be wide-spread, or if other solutions like hydrogen-fuel cells will take over the drone industry. Feel free to share your thoughts on this in the comment section.