Stirling Engines in the Palm of your Hand

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Treehugger loves Stirling engines-they have been the way of the future since 1816. They work on the basis of temperature differences and can be powered by just about anything- This Japanese toy version appears here to be powered variously by a dog, lunch, a cup of tea and an ice rink- that is versatility! We hope they manage to scale it up a bit. ::Japanese Science Magazine via ::Red Ferret

"The Stirling engine works by the repeated heating and cooling of a sealed amount of working gas, usually air or other gases such as hydrogen or helium. When the gas is heated, because it is in a sealed chamber, the pressure rises and this then acts on the power piston to produce a power stroke. When the gas is cooled the pressure drops and this means that less work needs to be done by the piston to recompress the gas on the return stroke, giving a net gain in power available on the shaft. The working gas flows cyclically between the hot and cold heat exchangers.The working gas is sealed within the piston cylinders, so there is no exhaust gas, (other than that incidental to heat production if combustion is used as the heat source). No valves are required, unlike other types of piston engines." ::Wikipedia