That's the theoretically part - there are processes that will capture the energy generated that would've otherwise become heat, but that only affects the timeliness. Given enough time, all workable energy generated by a heater would become heat, even if you had to wait for the matter itself to decay trillions of years from now when all the stars have long since breathed their last breath.

Also has somebody watched Technology Connections by any chance?
Heat pumps are so cool - if you showed onw to someone even a hundred years ago, even knowing what electricity was, they'd think it was magic.