Forget the mousetrap. Building a better lightbulb has been a constant — and profitable — pursuit ever since Humphrey Davy first invented the arc light circa 1810. Along the way, there have been major breakthroughs, including proto-light bulbs, carbonized-paper bulbs, and carbonized cotton-fiber bulbs. In 1906 General Electric patented a method for producing tungsten filaments that fit neatly inside a bulb, a feat that eventually transformed the power company into a global industrial giant.
While manufacturers have made advances in lighting during the past 70 years (think halogen bulbs and fluorescent tubes), none has come close to replacing the tungsten-filament lamp. Likewise, neon lights, in use for decades, remain just about the only lights ever used to illuminate outdoor signage. This is set to change, however. As Rich Marshall, vice president of construction at Home Depot, predicts: "The conventional lightbulb's days are probably numbered."
The reason? Look at your watch. The same kind of light-emitting diode (LED) that illuminates a $6 digital watch from Wal-Mart will likely change how the company one day lights its outdoor signs. In fact, a growing number of retailers, including Home Depot, are already switching to solid-state lights for their outdoor signage.
The light switch makes sense. Lamps powered by LEDs, which were first fabricated by GE in the 1960s, are more durable and more efficient than traditional incandescent lights. In fact, a study prepared by Chicago-based Navigant Consulting for the U.S. Department of Energy estimates that, by 2025, if price and performance targets are achieved, indoor and outdoor LED lighting could save the country approximately 114 billion kilowatt hours, or roughly the equivalent electrical output of about 14 large power plants.
Eat at OE'S
Initial costs of LEDs, which generate quantums of electromagnetic energy (photons) by zapping atoms in a semiconductor chip with electricity, run high. Indeed, since the output intensity of even the brightest LEDs today is low compared with incandescent, fluorescent, or halogen lights, the price of an LED lightbulb is about 10 to 20 times more than equivalent incandescent, fluorescent, or halogen lights. But in the long run, LED devices can generate big savings in energy consumption. Jagdish Rebello, a senior industry analyst at iSuppli, a semiconductor market-research firm headquartered in El Segundo, Calif., says LEDs consume about 10 percent of the power of incandescent lamps.
The benefits go well beyond lower electric bills. Since they produce little heat, solid-state lights aren't fire risks. And unlike neon, LED lights rely on an array of diodes. Hence, LED-illuminated outdoor signs don't suddenly develop missing or flickering letters if one light goes out. "With LEDs, there are thousands of individual lights," explains Marshall. "You could probably lose 50 percent of them before you actually had a letter that would appear dark."
In addition, LEDs aren't nearly as fragile as traditional lamps, and rarely break when dropped. In fact, long life is a real selling point of solid-state lights: LEDs can shine brightly for five years or more — a span researchers are looking to increase. "Your down time is negligible," says Marshall. Home Depot is currently installing semiconductor-illuminated signs from GE LED Solutions at all of its new and remodeled stores.
Within a few years, improved LEDs may begin replacing conventional lighting in virtually all applications. Automobile makers are already using LEDs in the brake lights of cars. And researchers at Rensselaer Polytechnic Institute have developed a new type of reflective coating that effectively reduces mirror losses by half, lowering the number of LEDs needed to illuminate an area. Eventually, those sorts of advances will drive down the costs of LEDs. "In another three to five years, we're going to see this new technology in the marketplace," says E. Fred Schubert, the Rensselaer electrical engineering professor who headed the research effort. "LEDs will be the most important light source of the future."
In the meantime, LEDs are already transforming a venerable American institution: the retail holiday display. This year, Saks Fifth Avenue is covering the front of its flagship New York store with more than 50 LED-illuminated metal snowflakes. Measuring between 8 and 20 feet across, each snowflake is ringed with three lines of LED lights. Management at the retailer, which plans to use the display for at least four years, expects the LEDs will last the life of the project. Says Tim Wisgerhof, Saks's window director: "With regular lights, it would have meant total refurbishment of every single light every year."
John Edwards is a freelance writer based in Gilbert, Arizona.