Power from friction
Harvesting energy from rolling tyres to provide power to the battery in electric vehicles is a concept that excites tyre engineers ever since Goodyear developed its concept tyre BH-03 that can generate electricity to charge the car battery. The idea was to take advantage of piezoelectricity, the electric charge that builds up in certain materials as they are squeezed or pressed. Tyres, as they roll, get deformed constantly and Goodyear engineers worked on generating power from this action.
The idea of scavenging friction energy from rolling tyres has evolved further. Researchers at the University of Wisconsin-Madison recently came up with a nanogenerator that could make vehicles more efficient by deriving power from the friction of rolling tyres. Xudong Wang, the Harvey D. Spangler fellow and an Associate Professor of materials science and engineering at UW-Madison, and his PhD student Yanchao Mao have been working on this device for about a year. The team, which also includes Dalong Genga and Erjun Liang, was able to demonstrate the device using a miniature remote-controlled Jeep.
“Nanogenerator was first developed in 2007 using piezoelectric nanostructures to harvest low-level mechanical energy,” Wang told Polymers & Tyre Asia in an exclusive e-mail interview. “Its nanoscale building blocks enable higher sensitivity and higher efficiency compared to bulk structures. Now, the nanogenerator concept has been broadened to the principle of the triboelectric effect (i.e. triboelectric generator), where the contact between two dissimilar surfaces creates charge distribution, and thus inducing current flow externally,” he said.
Wang explained: “The triboelectric effect is applied in our energy harvesting strategy from the tyre friction. In our design, we take the advantage of the contact between the tyre and ground, which are regarded as two dissimilar materials to create charge separation. Our design allows immediate draining of the induced charge once the tyre surface moves away from the ground. Continuously rolling of tyres will continuously produce charge to the tyre surface, which can thus generating continuous current pulses.”
PTA News Bureau
(Full text in PTA August/ September issue)