there is no known substance that can block magnetic feilds.
the difference between your setup and a coal fired setup is that the energy required is supplied from outside the system namely coal
in your system as soon as you start to draw current from generator a back emf will be produce. additional energy must be supplied to countract the back emf.
the difference between your setup and a coal fired setup is that the energy required is supplied from outside the system namely coal
in your system as soon as you start to draw current from generator a back emf will be produce. additional energy must be supplied to countract the back emf.