The bulb makers face a tough problem. Their businesses were built on customers who regularly replaced light bulbs. How do you make a profit when new lighting may commonly last 50 to 100 times as long as a standard bulb? Compact fluorescents, which use less than one-third the power and last up to 10 times as long as standard bulbs, have replaced incandescent bulbs in many homes and offices.

In some types of commercial buildings, L.E.D.’s are rapidly replacing older products. The industry seems convinced that new lower-cost L.E.D. bulbs, with their improved efficiency, will eventually become the chief substitutes for incandescent bulbs in homes.

Image The Empire State Building may soon use computer-controlled L.E.D.s. Credit... Michael Nagle for The New York Times

L.E.D.’s, including new bulb types and applications, dominated the exhibits at Lightfair, the lighting industry’s annual trade event held in May in Las Vegas. Traditional tungsten bulbs were largely absent. L.E.D.’s were shown for street and parking lot lighting, under-counter lighting, residential bulb replacements and office lighting. They are being used in commercial refrigerators, as substitutes for fluorescents and for illuminating the outside of buildings, allowing for easy color changes. Television production studios are installing L.E.D.’s to save money and eliminate the need for climbing in the rafters to change bulbs or filters.

The problem, though, is the price. A standard 60-watt incandescent usually costs less than $1. An equivalent compact fluorescent is about $2. But in Europe this September, Philips, the Dutch company dealing in consumer electronics, health care machines and lighting, is to introduce the Ledino, its first L.E.D. replacement for a standard incandescent. Priced at $107 a bulb, it is unlikely to have more than a few takers.

“L.E.D. performance is there, but the price is not,” said Kevin Dowling, a Philips Lighting vice president and past chairman of the Next Generation Lighting Industry Alliance, an industry group that works with the Department of Energy. “Even at $10 to $15, consumers won’t buy L.E.D. bulbs,” Mr. Dowling said.

The L.E.D., a type of semiconductor, generates light when an electric current is passed through positive and negative materials. Energy is given off in the form of heat and light. Different colors and greater efficiency are created by altering the composition of the material. Typically, a compact fluorescent bulb uses about 20 percent of the energy needed for a standard bulb to create the same amount of light. Today’s L.E.D.’s use about 15 percent. Next-generation bulbs still in the labs do even better.