There are lots of former and current clames of working free energy
devices, But never any proven beyond any dought that it worked and none
have ever gone into commercial production or use.
But it is possible that any one that did work may have been threatened
/ paid off by the big oil companies / Countries to keep it quiet after
the initial clams that it worked.
There have been some proven very large increases in efficiency in
electric motors and you have see automobile gas mileage double in about
the last 8 years from about 18 to 20 MPG to 33 to 42 MPG.
Do a search on the name Kesh in Brazil they have a small fan electric
motor that uses only one third the electricity of most fan motors and
supposably can be upsized to larger motors, Why they are not working
with a large company like General Electric I do not know, Like a lot of
inventions the inventors seem to be over protective to the point that
they never make it to market ?