<Li> Any device picking up minimal amounts of energy from the natural electromagnetic radiation around it, such as a solar powered motor . </Li> <Li> Any device powered by changes in air pressure, such as some clocks (Cox's timepiece, Beverly Clock). The motion leeches energy from moving air which in turn gained its energy from being acted on . </Li> <Li> The Atmos clock uses changes in the vapor pressure of ethyl chloride with temperature to wind the clock spring . </Li> <Li> A device powered by radioactive decay from an isotope with a relatively long half - life; such a device could plausibly operate for hundreds or thousands of years . </Li>

There is no such thing as a perpetual motion machine