5 Responses

1. No. That would violate the first law of thermodynamics and be a perpetual motion machine. You cannot get more energy out of a generator than you put in, in fact, you get less due to the losses in running the generator.

2. oemen is right. a proper mechanical engineer’s explanation.

3. Life would be so beautiful, if only what you say could be true! But, alas! it is not so easy. Then who would supply the losses? If the generator and the motor are 100% efficient, then it might be possible. But, the generator & the motor have efficiency in the range of 80% to 85% only. Let me explain.

   Assuming you start a motor coupled to a generator, initially by some temporary means, say, a battery or by some external mechanical means. Once the motor is started, the generator revolves and produces electric power. Your arguement is that – now, connect the electric power output from the generator to the motor and remove the starting means, so that the generator supplies the electrical power required by the motor and the motor supplies the mechanical power required by the generator. Both, complementing each other. That is your arguement. Isn’t it?

   Now, assume the generator is rated for 10kW output. Then, with even 90% efficiency, it requires 11.11kW mechanical power input. For the motor driving the generator to supply this mechanical output, with even 90% efficiency of the motor, it requires 12.35kW electrical power input.

   Now, initially assuming that you are able to supply the initial electrical power required by the motor – that is 12.35kW – from some external means, and the motor drive the generator. The generator output would be 10kW as rated. Now, if you connect this generator output of 10kW to the motor, who would supply the balance 2.35kW input required by the motor? So, in such a scenario, both would come to a standstill.

4. Nope :0(

   Electric generators are not 100% efficient. energy is lost along the way, as heat (due to friction) and sound and things like that. therefore electric energy generated isn’t equal to kinetic energy put in.
   do this many times, by feeding the energy back into the generator, and you’ll end up with the energy dwindling away over time till the generator is stationary.

5. In any machine that converts one kind of energy to another, the useful energy you get out is always less than the energy you put in. The ratio of energy out / energy in is the efficiency, and it is always less than 100%.
   The rest of the energy is lost as heat.
   If you connected a generator to a motor and used it to drive the generator, it would stop almost instantly, and the generator and motor would get a little bit warmer.