You might learn something with this Stirling engine model

If you ever wanted to turn the heat from your cup of tea or coffee into piston power, I have just the gadget for you. It’s a Low Temperature Differential�Stirling engine model. Invented by Robert Stirling back in 1816, this engine produces power from temperature differences. You can place it on top of something warm [...]

EMULEX EMS TECHNOLOGIES EMC ELECTRONICS FOR IMAGING ELECTRONIC DATA SYSTEMS