Over unity machine?
This is a machine whose efficiency is greater than 100%, that is, you get out more energy than you put in. It’s just another circumlocution which is used for “perpetual motion machine” since nowadays most people realize that perpetual motion is impossible. Plans for perpetual motion machines have been around for a long time, haven’t any of them worked? The first drawing of a perpetual motion machine dates from the 13th century. Thousands of people have tried to make over- balanced wheels, recirculating waterwheels and strange magnetic devices. None of them has worked. Since the discovery of the first and second laws of thermodynamics we have known why a perpetual motion machine is impossible.