The obsolescent incandescent.

• Author: Roodman, David Malin
• Position: Replacing the ordinary light bulb with the compact fluorescent camp, CFL

In an age of rapid technological development, Thomas Edison's unpresuming incandescent light bulb has shown remarkable staying power. Now, however, a green revolution may be on the verge of making this technological centenarian as old-fashioned a way of producing light as the gramophone is of reproducing music.

The young upstart is the compact fluorescent lamp (CFL), first introduced in the late 1980s by the Dutch company Philips, past popularizer of the cassette and compact disc players. The CFL, which squeezes efficient fluorescent lighting technology into a package comparable to standard bulbs in size and color quality, has recently enjoyed a world-wide sales boom of its own. Since 1988, sales have grown more than 30 percent a year, from about 45 million to more than triple that today.

Even with this success, the estimated 160 million CFLs sold in 1992 were easily outshone by the 9 billion incandescents purchased that year. But CFLs last so long that each one in use supplants a succession of 10 regular bulbs. Thus while CFLs comprised less than 2 percent of the lamps of this size sold in 1992, they have already taken a healthy 13 percent bite out of the market in terms of hours of lighting capacity sold.

Meanwhile, in the Western European countries where the CFL is strongest, sales of regular bulbs have stagnated. This complementary trend should only spread as CFL growth continues apace. Annual production of the new lamps is likely to pass 300 million in 1996, according to Evan Mills, assistant director of the Center for Building Science at the Lawrence Berkeley Laboratory in Berkeley, California.

To appreciate the inefficiency of an incandescent bulb, all a person has to do is touch one - but not for too long. A standard bulb puts out more heat than light, because it expends more than 90 percent of the electrical energy it draws just keeping its tungsten filament hot enough to glow.

In contrast, the modern CFL embodies several decades of innovation in efficient fluorescent lighting. It uses electricity to excite a tube-confined gas, which then radiates ultraviolet rays. Phosphors on the inner surface of the tube convert this radiation to visible light, and much less heat. As a result, a CFL is four times as efficient as an incandescent bulb.

Wherever the new lamp has caught on, it has saved money for both consumers and utilities by slowing the growth of expenditures on electric power plant operation and construction. And by requiring...