Engineers from the University of Southern Denmark have developed an ingenious technology that enables a drone to fly indefinitely without ever returning to the ground. Utilizing a docking mechanism, advanced sensors, and an artificial intelligence system, the drone can identify power lines whenever it needs to recharge its batteries. It approaches the high-voltage cables, latches on, and draws electricity, effectively functioning like an electric vampire.

“The drones would be able to essentially live on the grid and operate completely autonomously for extended periods with no need for human interaction,” the development team explained via email.

The concept of using power lines to charge drones originated in 2017 when Emad Ebeid, a professor at the University of Southern Denmark (SDU), was exploring drone applications and identified power line inspection as a promising area. Ebeid noted that the existing inspection process, relying on helicopters and ground personnel, was both costly and inefficient. Drones emerged as a natural alternative for this expensive maintenance effort, capable of remote or autonomous operation to oversee the lines. However, drones’ limited battery life—typically maxing out at 40 minutes—posed a significant challenge, necessitating a permanent human crew nearby, which contradicted the goal of autonomous operation.

To achieve complete autonomy, the drones needed a way to recharge without human intervention. The solution lay in the power lines themselves. Ensuring that a drone could find, securely latch onto, and draw electricity from a power line proved to be a complex design problem.

The first issue was enabling the drones to interact with the power lines. “By default, drones are not meant to physically interact with anything other than the air during flight and the ground during landing,” the researchers explained. Initial tests with early maneuvers showed unpredictable behavior when contacting power lines, necessitating the presence of a skilled safety pilot to prevent potential damage or wildfires.

The team programmed the drone to approach the power line from below, reducing collision risks. They outfitted the drone with grippers, essentially insulated clamps that grab the power line without conducting electricity to the drone itself. The gripper mechanism activates through an electromagnetic process when the drone’s software detects it is in the correct position, ensuring a secure attachment.

The final design challenge was converting the power line’s high voltage into a manageable form for the drone. Typical power lines carry between 1,000 and 800,000 volts, while drones require only about 9 volts. High-voltage transformers, which can weigh hundreds of tonnes, were not a viable option. Instead, the team utilized inductive coupling, harnessing the magnetic field around the cable to induce a current in the drone’s energy harvester, similar to how a wireless phone charger works. Depending on the cable’s voltage, a 9.4-pound drone requires between 30 minutes to six hours to charge.

After seven years of development, the system was successfully tested at HCA Airport in Denmark. The drone performed five recharging sessions without human intervention, allowing it to fly for two uninterrupted hours—an impressive increase from the usual 30 minutes. Theoretically, this could enable the drone to fly indefinitely.

The next steps involve optimizing the system and testing its durability under adverse weather conditions. “It will be challenging to weatherproof the system and also make it resistant to very high voltages,” the team noted. Ensuring the system’s durability and public safety is crucial, as is preventing potential jamming or hijacking.

Before widespread adoption, issues like the cost of the electricity drawn from the lines need resolution. The drone, in a sense, “steals” power that would otherwise be unused. However, the researchers believe utility companies will eventually adopt this technology to reduce the substantial costs of power-line monitoring and maintenance.

While currently a research and enterprise project, this technology could eventually be used by drone enthusiasts and various industries, potentially transforming operations with 24/7 monitoring and optimization. With approximately 25 million miles of power lines worldwide, enough to circle Earth 1,000 times, the potential applications and benefits of this technology are vast, ranging from cost savings to life-saving emergency operations.

As the inventors conclude, the applications and benefits of this technology are “as vast as the global power-line network itself.”

By Impact Lab