Reversing Piezoelectric

[mishima]

I bought an old cup warmer from a thrift store that uses a piezoelectric plate and was wondering if I could reverse it somehow to generate electricity from heat. This doesn't need to be practical, I just wanted to know if it would generate a few mV on my multimeter.

I got the idea from somewhere on the internet but can't find it again now.

Anyone have any ideas/know what im talking about?

 

[vk6kro]

That would be a Peltier device.

Yes, you can get electric power out of it and probably more than a few mV.

In fact, if you heat some water in it and then remove the power source and measure the voltage at the input terminals, you would probably measure several volts.

There is a problem in that the output depends on the difference in temperature between the two sides of the Peltier device, so you have to have one side colder than the other.
You can't just dunk the whole thing in hot water to get output.

However if you can have one side of the device on a heat sink to carry any heat away, and heat the other side, then there should be quite a bit of electric power generated.

This is one of the few ways you can generate electricity directly from heat.

 

[mishima]

Awesome, "Peltier"...yep that was it. Im designing a project for high school students who are making solar cooker ovens and I thought I might try throwing one of these into it and seeing what happens.

I also got a thermocouple like for a water heater from a hardware store and was going to try that as well on the multimeter.