Light-emitting diodes (LED) are compound semicondutor devices that convert low-voltage electricity to light. General Electric scientists invented the first application of LED in the 1960s. Unlike conventional lamps that can shatter,  LED are resistant to shock and vibration. The solid-state nature of LED means no filaments to break or moving parts to fail.

The advantages of the technology vary with the application. Features of LED include 90% energy savings over similarly-bright incandescents, lamp-life minimum of 50,000 hours, and excellent cold weather start-up and performance. The disposal issue faced with mercury vapor and fluorescent lamps and ballasts is obviated.

Early applications included traffic signals replacement; the technology offers color rendering choices and significant lamp replacement and energy usage advantages over legacy incandescent traffic signals.

Applications have expanded to include parts for televisions, building interior and exterior lighting, signs, focused retail displays, flashlights, elevator call buttons, commercial and residential fixtures (those changing colored lights in your hot tub are LED), and transportation and street lighting.  The LED industry is estimated to have grown 50% year on year between 1995 and 2004, and for the period 2004-2009 the US market is expected to grow from US$3.7 B to US$7.3 B, the highest growth being in transportation uses (projection courtesy Oppenheimer research).

Use in transportation infrastructure continues, South Korea and Los Angeles, Califonia having recently announced major LED initiatives.

Remote monitoring capability facilitate “smart grid” applications; flashing street lights on the curb will one day signal emergency responders regarding the location of a call.

Photo of exterior fixture

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