Whenever people walk, they create a lot of wasted energy. Engineers at the University of Leeds are developing a way to capture the kinetic energy produced when soldiers march and use it to power their equipment. The new system designed to convert foot-power into battery power could help troops reduce the weight of their packs by up to 10 kilograms.

The two-year project will consider the optimum placement of the energy harvesting devices. Possible options include back-pack straps or somewhere around the knee to provide active support, capturing energy but also cushioning the impact when legs are bent, joints compressed or boots strike the ground. The devices will use high-tech ceramics and crystals as piezoelectric transducers to convert mechanical stress into an electric charge.

“Heavy packs can severely limit a soldier’s mobility and also lead to long-term health problems,” says Andrew Bell, director of the Institute for Materials Research at the University of Leeds. “Ground troops typically carry electrical equipment, including flashlights, personal radios and communications systems.”

The typical pack weight of an infantry soldier on a six-hour patrol is around 75 kilograms, with batteries making up about 8 percent of the load. Ammunition and water make up much of the rest.

“As well as the obvious green issue of using so many batteries, [energy harvesting] could also reduce a soldier’s pack weight by around 15 percent,” Bell points out.

A similar idea has been used in cars for some time where braking force is stored and later used to drive the vehicle forward. However, harvesting energy from people walking has always proved difficult due to the flexibility and strength of the materials required, and the fact that everyone’s walking patterns are different.

Bell believes that he and his colleagues will succeed where others have failed, because they are taking a holistic approach. “By using the latest materials and electronics, combined with taking into account personal differences in walking style, we are confident we can make this work without adding to the burden or fatigue of the soldier wearing the device,” he explains.

Another key part of the project will be adapting radio equipment to run on a reduced power budget. The new low-power radios will run on standby, only boosting up to full power when an important message is received or a transmission is required.