Piezoelectrics Promise To Create Energy from Everything

Fascinating!

Wouldn't it be great if your cell phone or mp3 player could charge itself? What if your house could generate electricity from the noise of the cars on the road? Or if the waste heat generated by your air conditioner could help put a dent in that expensive summer electric bill? As the demand for cheaper and more renewable energy sources increases, piezoelectrics - a class of material that produces an electric potential when mechanically deformed - may hold the key to unlocking the energy flowing all around us.

Piezoelectrics themselves are not new. In the early 1800's, Pierre and Jacques Curie demonstrated the piezoelectric properties of some natural crystalline materials, such as quartz and sugar cane. What they didn't predict (although they did verify it once Gabriel Lippmann predicted it in 1881) was the converse effect - piezoelectric materials deform when a voltage is applied.

Strange Properties: A piezoelectric material produces a voltage when deformed, and deforms when subjected to a voltage, leading to all kinds of practical applications. The deformation in the diagram is highly exaggerated. Credit: Wikipedia Commons

Recently, however, researchers are trying to exploit piezoelectrics not for their accuracy, but for their power-generation capabilities. Since World War I, piezoelectrics have been used in sonar systems to detect pressure changes in the water and produce a resulting signal voltage, giving valuable information to their operators. But what if that sound could be converted directly into power for the electrical grid? One could imagine freeway walls and medians covered with panels absorbing the sound of passing cars and trucks and feeding it directly into the grid - fulfilling the dual purpose of reducing freeway noise while simultaneously producing energy.

There are applications of this technology already in place - certain dance clubs in Europe utilize dance floors with piezoelectrics to help power the lights. What would really be useful to the consumer, however, would be small piezoelectric systems that could assist in powering personal electronic devices.

Read the whole thing.

When I was an undergrad studying mechanical engineering at Virginia Tech, I was a research assistant at the Center for Intelligent Materials Systems and Structures (CIMMS), doing research on piezoelectric materials. (Piezoceramic actuators to be exact.) While I didn't get into stuff as sophisticated as what is discussed in this article, it was a great opportunity for becoming more familiar with the science behind piezoelectric materials and their potential applications. I was able to make a pair of stereo speakers by attaching piezoelectric materials to a Coke can. The material would vibrate the can based on the incoming audio signal, which would then produce sound. I did the same thing with a window pane. (It had great treble, but horrible bass.)

Other potential uses of piezolectrics include sensors for detecting failure in aircraft bodies, silencing submarines by creating destructive interference with sound traveling through their hulls, etc. Here is a list of current research projects at CIMSS and a good summary of piezoelectricity on Wikipedia.

As much as I love economics, reading stuff like this really makes me miss engineering.