This can also run off sunlight. Ever wanted a engine that can run off the heat from your coffee cup? Like toys that are hard to explain and amazing to watch? Like precision pieces of equipment that are beautifully engineered? Love science? Want a gift for the person that has everything? If so you will want a Stirling Engine.The engines I offer are fully assembled and not a kit.These are the low temperature versions of a stirling engine that can run off hot water from a coffee cup, heat from a router, and so on. I have had these run while sitting in the sun at street fairs. Stirling engines operate by using a external heat source rather than a internal heat like a normal engine.The easiest way to use them is get your normal cup of coffee in the morning, put the sterling engine on top of the coffee cup, give it a slight push to get it going and as long as the coffee is hot it will continue to run. These are precision pieces of equipment but are finally available at a economical price.If you would like to see a video of them operating look at Your favorite Video Streaming site and look up Low temperature Stirling Engine. I am sure you will want one. Want one that will power a light then look at my other Stirling Engine.All my units I sell are personally tested by me on a hot cup of water to make sure they work.