Thomas Edison’s 132-year reign is ending. By federal law, the phaseout of his trusty lightbulb begins in 2012. But the heir apparent–spiral compact fluorescent lamps (CFLs)–are far from perfect: Break them and you release mercury into the air. That’s why insiders’ hopes are with LED bulbs, which use a fifth of the energy that incandescents do and last up to 50,000 hours–five times longer than CFLs. One hiccup: A single bulb can cost $50. (The one to the right is about $40.) Prices have been slow to fall.
We’ve seen this story before. CFLs were once $30 and now go for $2. But LED bulbs rely on expensive semiconductor chips, and greater manufacturing scale and technological advances are necessary to make their parts much cheaper. “If you get it under 10 bucks,” says Keith Scott, VP of business development for LED manufacturer Bridgelux, “that’s a pretty nice point in consumer spending.”
Why does it look like that?
Because nobody wants shoppers to say, “What the heck is this thing?” LED light comes from a small, flat surface–so while the bulb does have to be able to screw into a light fixture, it doesn’t actually have to be shaped like Edison’s bulb at all. And maybe one day it won’t be.
1 Printed circuit board:
Complete LED components are mounted on a printed circuit board, sometimes by hand. Because of the board’s complexity, it would be difficult to automate production.
LEDs start as wafers of silicon carbide, which are topped with indium gallium nitride. Costs can reach $8 a unit. Some companies are working to make bigger wafers, onto which LEDs can be built less expensively. Bridgelux says it’s working on using a wafer that’s more common in computer chips, which could save 75% and be available in about two years.
3 Outer casting:
The most efficient LEDs typically produce blue light. The bulb’s outer casing must then be coated in phosphor, turning that blue into a more natural white. That requires buying rare-earth metals from China. To nix the coating, researchers are developing a green LED to mix with red and blue ones to make white.
Unlike incandescents, most LEDs don’t work on alternating current, the U.S.’s standard form of electricity. They need drivers (which can cost $4) to convert the juice into direct current. Upside: Drivers let LED bulbs be dimmed, unlike some CFLs.
5 Head Sink:
LEDs aren’t as hot as incandescent bulbs, but still degrade in heat without protection. A conducting piece of metal–often aluminum–sends heat away from the bulb. These sinks are currently quite large and can cost $3 to make. Companies are looking into making smaller ones, saving metal (and money).