• Question: Can I connect an alternator to an electric motor to generate electricity endlessly on its own?

    Asked by caseym to Ed, Katie, Sam, Steve, Vera on 20 Jun 2011.
    • Photo: Katie Marriott

      Katie Marriott answered on 19 Jun 2011:

      It has been a very long time since I have done physics and even then I wasn’t very good at it so I am not sure!

      I think it could work but I really don’t know enough about it to say.

    • Photo: Ed Morrison

      Ed Morrison answered on 19 Jun 2011:

      I think you can use a motor to generate electricty. Of course, you can’t violate the laws of thermodynamics so you need a fuel source for the motor.

    • Photo: Steven Daly

      Steven Daly answered on 20 Jun 2011:

      The problem is that any engine is not 100% efficient – that is that not all the energy you put into the generator will come out as electricity. Some will become heat, some sound, etc. You have to put some energy into the alternator to make that work, which usually is some mechanical force like a turbine powered by steam. The way you have described it is actually less efficient than just having an electric motor or an alternator – you will get less electricity out of the alternator than you put into it with the motor. This is as I said because of energy loss in the system.

    • Photo: Sam Tazzyman

      Sam Tazzyman answered on 20 Jun 2011:

      No, as Steven and Ed have said, which is a shame because then there would be endless free energy for all!

    • Photo: Vera Weisbecker

      Vera Weisbecker answered on 20 Jun 2011:

      Again my answer was somehow deleted so apologies if you get this twice. Steven and Ed are right that you need something, fuel or so, to keep the system going. A long time ago, in the middle ages, people were trying to come up with a machine that would move, without additional energy, in perpetuity – that is why they called it the “perpetuum mobile”. However, no matter how hard you try, there will always be something to slow down the system (e.g. friction at the bearings) so that it simply can’t work.

Comments