Light-Emitting Diodes: Chasing White Light

While LEDs use very little electricity, they also produce relatively small amounts of light. This light is highly concentrated and easy to focus, making it effective in some applications, such as task or display lighting. To use LEDs for area or ambient lighting, manufacturers collect multiple LEDs in a single fixture; getting enough output and an attractive color of light, however, has been challenging. Complicating matters, LEDs vary tremendously in quality; inexpensive LED lamps and flashlights tend to have inconsistent color temperature and light output.

When their light is effective, LEDs offer great potential for energy efficiency. Although current LED fixtures average 30–40 lumens per watt (lpw), the Solid-State Lighting Program at the U.S. Department of Energy (DOE) estimates that LED fixtures are capable of achieving an efficacy of 160 lpw. By comparison, incandescent lamps typically produce 10–18 lpw and compact fluorescent lamps (CFLs) 35–60 lpw. LEDs also have the significant advantage of not containing mercury, which is a disposal and breakage hazard in fluorescent and mercury-vapor lamps.