I know this can't be done, else everyone would be doing it, this question is more of a "why can't it be done? and what are the difficulties that make this impossible?" rather than a "Why is no one doing it?". We have a motor, naturally we would connect it to our mains and draw power, the shaft of this motor is connected to a load through a belt. What would happen if we connect a generator of similar specifications to this belt therefore generating the power which would be used by the motor? This generator would be connected to a battery recharging this battery which in turn powers the motor, at a first glance, it would seem that this system is self powered and therefore could run indefinitely and without consuming power. Ideally we could manufacture self powered motors (in the same casing) so we would not have to worry about designing such systems and finding compatible motor/generator. What I think would be the problem. - I understand there would be losses in the system and power factor correction would be a very important concern here. Could this not easily be accounted for in the design? - Maybe its got something to do with the fact that all kinetic energy is soaked up by the generator therefore making this system useless unless you want to power a fan or something light. Me and my friend had considered the possibilities and we strongly feel like we are missing one of the most obvious and important points.