Harvesting Sound Energy From Passing Cars
As engineering grad student “Mechanical Attraction” puts in his writeup, “There is energy everywhere around us in many forms.” To most of us, this might mean solar, or perhaps wind energy or hydroelectric power comes to mind. On the other hand, what about sound? This form of energy occurs around us all the time, and Mechanical Attraction made a device to collect it from passing cars, a consistent source of noise.

His project uses a pair of piezoelectric wafers attached to beams designed to have a resonant frequency that picks up the most energy from passing cars. The length of the beams was calculated using the Euler-Bernoulli beam theory, and beams made out of both aluminum and nylon were tested to see which performed better. A bridge rectifier was used to turn the fluctuating power from the piezoelectric wafer into DC current, which then goes through a capacitor before passing the output voltage to an Arduino Nano used as a measurement device.

After laboratory testing with a speaker, the whole setup was then moved for a “live” street side test, which produced more consistent results with aluminum. Though an interesting experiment, this device’s potential for energy harvesting isn’t likely to change the world any time soon. Thee voltage of the more consistent aluminum oscillators reached only .225 volts, and nylon peaked at .275 volts!


