I’ve long been fascinated by Stirling Engines. These are temperature differential engines. That’s a complicated term which really just means as long as you have a difference in temperature on the drive component of the engine, the engine will run. In even simpler, although slightly inaccurate terms, wherever you have a source of heat or cold you can get a stirling engine to run.
These engines should be used in heat recovery, and power generation. They are remarkably efficient and since they can be made to use waste heat or waste cooling, they should be found everywhere.
How it works
There is a wealth of resources available to explain how a Stirling engine works, but this diagram should get you started:
Building Process:
Engine Run:
Where to find it:
http://www.banggood.com/DIY-Steam-Engine-Model-Educational-Toy-Kits-p-1017323.html
