By Dhananjay Khadilkar, Source: Scientific American

PARIS—On April 7, 2013, Kenya’s Peter Some won the 37th Paris Marathon with a time of 2:05:38. A surprise winner, Some missed the event record by only 27 seconds, thus depriving him of a place in running history. He need not have worried; unknown to him and thousands of fellow marathoners, they were all nonetheless part of a historic event. As they ran across the Avenue des Champs Élysées and thumped their feet on 176 special tiles laid on a 25-meter stretch, the athletes generated electricity.

These special “energy harvesting tiles” were developed by London-based Pavegen Systems. The power thus generated can be used to run low-voltage equipment such as streetlights and vending machines. The concept is the brainchild of Laurence Kemball-Cook, who founded Pavegen in 2009 to commercialize it. “The Paris Marathon is the first of many such projects that will enable us to realize our goal of taking this technology to retail sites, transport hubs, office blocks and infrastructure spaces,” he says.

Pavegen uses what it calls a hybrid black box technology to convert the energy of a footstep into electricity, which is either stored in a battery or fed directly to devices. A typical tile is made of recycled polymer, with the top surface made from recycled truck tires. A foot stomp that depresses a single tile by five millimeters produces between one and seven watts. These tiles generate electricity with a hybrid solution of mechanisms that include the piezoelectric effect (an electric charge produced when pressure is exerted on crystals such as quartz) and induction, which uses copper coils and magnets. The marathon runners generated 4.7 kilowatt-hours of energy, enough to power a five-watt LED bulb for 940 hours, or 40 days. “We came together for Paris Marathon to highlight how technology is really going to change the way people think about energy,” says Joe Hart, senior vice president of Segment & Solution Marketing at Schneider Electric.

Easy power collection sounds promising, but implementation is challenging. As Kemball-Cook says, “Installing the tiles in the ground is one of the hardest things to do as they have to be very durable, weather resistant and should have high fatigue resistance as well. Also, these tiles could get vandalized.”

Hart says that in a couple of years, Pavegen’s technology could become visible and apparent in a number of areas, not only as power units but also in security applications. “Each of those tiles has wireless capability—using which, we can analyze movement and optimize floor management.”

Pavegen is not alone in harvesting human kinetic energy to generate electricity. Max Donelan, founder of Canada-based Bionic Power, which has developed a wearable knee brace that harvests energy while walking, says the braces “can be useful when you need electricity without having to rely on the power grid. For example, our knee braces are being developed for military use in places like Afghanistan where battery cells are exorbitantly expensive.”

Energy-harvesting tiles may be just one step for man, but taking many such steps may lead to a more powerful and sustainable future.