Abstract: The present invention is a power regenerating device comprising of a hollow pressure cabin with an exhaust valve and a pressure gauge, one or more sets of suction devices at the inlet of the pressure cabin, and a set of windmill generators at the outlet of the pressure cabin, in which the set of windmill generators is composed of multi fan-type windmill generators connected in series. Once the air enters into the pressure cabin through the suction devices, the control valve at the outlet will be opened and the pressed air will flow out through the outlet to drive the windmill generators, which in turn revolve and generate electric power, and output the power to the collecting bar and then to the rectifier. The power generating capacity of this regenerator depends oil the demand.