Afew percentage points of improvement in energy efficiency are rarely noteworthy, but those digits add up fast when the technology involved annually consumes several hundred billion kilowatt-hours of electricity worldwide. About two thirds of the juice used by American industry, for example, drives the countless electric motors running pumps, compressors, fans, conveyors and other devices in factories and plants nationwide, according to the U.S. Department of Energy. After a decade-long R&D effort, engineers have succeeded in wresting a bit more efficiency from these motors. And industry has just begun to take notice.