Ann Arbor city workers are installing light-emitting diodes, or LEDs, to replace about 1,400 street lights.

The eco-friendly city about 30 miles west of Detroit says it will be the nation's first to convert all downtown street lights to LED technology, which uses less than half the energy of traditional bulbs and could save the community $100,000 a year.

LEDs, small chips usually encased in a glass dome the size of a matchstick head, have been used in electronics for decades. They usually gave off red or green light, but a scientific breakthrough in the 1990s paved the way for LEDs that produce white light.