Science Buddies: "Ask an Expert"

Hi

I recently read that piezoelectric transducers are devices that convert mechanical stress into a voltage difference which generates electricity. So I am thinking about placing piezos on or beneath the accelerator,brake and clutch of a car so that when we apply stress on it it can generate electricity. So I am not very sure if this idea will work. And also what all can I do with the generated electricity? 1 possible thing maybe to store it in a capacitor and use it to charge phones. So any help would be appreciated

Thanks
Harshul

Hi Harshul,

After a bit of online searching I ran across a design for a piezoelectric battery charger that’s built into a shoe. It’s described at the following link.

http://www.popsci.com/powerwalker

You might be able to modify this design to fit the charger into the pedals of a car. But the shoe-mounted version may charge batteries more quickly. A small amount of electricity is generated each time the piezoelectric material is deformed. Walking will result in more deformations than actuating the car pedals.

I hope this helps. Please post again if you have more questions.

A. Norman

Thanks for the reply

Okay so you're saying that the piezos can be fitted inside the pedal, right? because previously i thought of keeping it ON the pedal. Keeping the piezos inside the pedal might generate a bit less electricity than the one you proposed but what I think is that there are lots and lots of vehicles and in India the vehicles have to be braked quite often, so generating electricity from the pedals can be a very novel concept. Morever I came across a piece of news saying that charging phones in the car adds to pollution by decreasing the mileage. So if that mechanism is replaced by this one we can also reduce pollution. This is what I think. Please tell me if it the right thought. And yes what all can be done with the generated electricity other than charging phones?

Harshul

Hi Harshul,

The piezoelectric generator would have to be positioned so that force from the driver’s foot is transmitted to the piezoelectric material. One way this might be done is to put the piezoelectric material on the pedal surface. There may be other options that could work as well.

Automobiles use an alternator driven by the engine to produce electricity for the engine’s ignition system, lights and accessories. Because the engine powers the alternator, any additional electrical demand will result in more fuel consumption by the engine. When you plug a cell phone charger into your car, the engine will use a little more fuel. And burning more fuel will result in more air pollution.
But the added electrical demand due to using a cell phone charger in a car is tiny compared with the energy needed to run the car’s electrical system. So eliminating electrical load from cell phone chargers in cars won’t have much effect on air pollution.

I hope this helps. Please post again if you have more questions.

A. Norman