during the energy crisis of the 1970s, he led the development of general electric’s pioneering energy-efficient lamp. he led the development of the watt miser (marketed as the f-40 watt miser), which was released in 1973. in 1976, he invented the first compact fluorescent lightbulb, but due to the difficulty of the manufacturing process for coating the interior of the spiral glass tube, ge did not manufacture or sell the device. other companies began manufacturing and selling the device in 1995. the smithsonian institution houses hammer's original cfl prototype.