City College of New York researchers, led by professor Yiannis Andreopoulos, are studying how to incorporate piezoelectric electricity generators into cars and planes, so they can convert the kinetic energy of motion into electricity. Their concept will be presented at the 62nd Annual Meeting of the American Physical Society’s (APS) Division of Fluid Dynamics, from 22 to 24 November, at the Minneapolis Convention Center.
The devices they designed are smaller than a match box, being only half an inch by one inch. These small piezoelectric gadgets could be mounted on a car’s roof or on an airplane’s fuselage, where they would vibrate, producing electricity. Of course, this is only a demonstrative experiment, the practical use of these devices wouldn’t be significant in these areas anyway, or they would not be felt much, since the powers they provide are much smaller than those produced by the actual engines.
When the device is placed in the wake of a cylinder – such as on the back of a truck – the flow of air will cause the devices to vibrate in resonance, says Andreopoulos. On the roof of car, they will shake in a much more unsteady flow known as a turbulent boundary layer. In Minneapolis, Andreopoulos and his colleagues will present wind tunnel data showing how the devices work in both situations.
“These devices open the possibility to continuously scavenge otherwise wasted energy from the environment,” says Andreopoulos.
Furthermore, placed in the wind, on the roof of the car, the piezoelectric toys could theoretically alter the aerodynamic properties and cause additional drag, which would move their energy source from the wind to the engine moving the truck or airplane, and indirectly to the fossil fuel.
So, it’s not the practical advantages that are interesting in CCNY’s experiment, by the theoretical principles that apply here, and could easily be used at larger scales to recover the energy otherwise lost in various systems, such as the moment when the car or the airplane brakes. Piezoelectricity is already used to generate a lot of power under the highways of Israel, so researching in this area still has potential.