In a Stirling engine, as with any other heat engine, there are two zones at different temperature, and the working fluid is moved between them to extract work. In the animation at the right ...

The model Stirling engine is a staple of novelty catalogues ... this design is that it appears not to have a regenerator, or heat store. This usually lies in the path between the two cylinders ...

Shunting ions around with electricity could produce enough heat transfer to replace greenhouse gas compression ... and the team has designed a four-step Stirling cycle to use its ionocaloric effect, ...