How can kinetic energy lost by a wheel?

We purchased and tried magnetic power generator is what we found: query Weronika A : How kinetic energy lost by a flying A flywheel possessing a higher rotational speed. No energy is supplied. The flywheel is utilised to turn a dynamo, and that energy is utilized by the generator for illuminating a bulb. The bulb remains connected until the wheel stops spinning. All of the energy is stored in the flywheel is transmitted to the piston. Part is lost. Please give two areas from which it is lost

Tesla's Generator