Physics Today December 2001

Physics Today December 2001: "A vital and growing use of energy is the generation of electricity. In the US alone, producing electricity costs $60 billion a year. But the cost of electrical energy should not be measured in dollars alone--there is the environmental cost of smog and carbon dioxide pollution associated with electricity production. About 20% of electricity is used for lighting. The most widely used sources of artificial illumination are incandescent and fluorescent lamps, but this is about to change: Solid-state lighting (SSL) devices promise to replace conventional light sources, with impressive economic and environmental savings. In the US, expenditures for lighting may be reduced by $100 billion over the period 2000-2020. By the year 2020, electricity used for lighting may be cut by 50%, sparing the atmosphere 28 million metric tons of carbon emission annually.1 Not only will SSL lead to energy and environmental savings, but it will change the way we think about lighting. SSL devices are vibration and shock resistant, and exceptionally long-lived. They will allow for a wide variety of lighting, including artificial lighting similar to natural daylight. Moreover, with appropriate circuitry, the color and intensity of the lighting can be controlled. Because SSL devices can be coupled to light pipes, light may be flexibly and efficiently distributed. SSL devices also offer interesting design possibilities--they can be manufactured as flat packages of any shape that can be placed on floors, walls, ceilings, or even furniture"