Let's say this first, because it isn't said nearly enough: The modern electric incandescent light bulb is an almost perfect consumer product, worthy of our admiration and praise. Measured on just about every axis -- cost, usefulness, reliability, attractiveness, practicability -- a standard light bulb beats out nearly everything else we consider dear to our lives. What else does so much so well for so little money, with so few hassles and no learning curve, safely and effectively, all the time?
The incandescent light bulb's near-perfection is, however, a mixed blessing. Electric light was invented in early 1800s by Humphry Davy and perfected later that century, in the form of a long-lasting bulb, by Thomas Edison. Innovation in incandescents has been remarkably static since then; the lights we use today have not changed substantially for decades. This is because the bulbs are so good. Incandescent bulbs so easily and reliably produce so much high-quality light that for the longest time we were all a bit blinded to their greatest flaw, inefficiency. More than 90 percent of the electricity consumed by a light bulb is wasted on heat.
When you think about it, the number seems incredible. Not just in terms of waste, but in the context of the human impact on our environment. Every time we switch on a light, we're contributing to global warming and the depletion of fossil fuels in a fantastically inefficient manner.
But who ever thinks about that? Who has ever asked for a redesigned light bulb? Much of what we find in this world is faulty or buggy, ripe for reinvention. Just about every product you can think of, starting with the PC and ending with toothpaste, could do with some kind of extreme makeover. The innocent incandescent light bulb does not seem like one of them.
Yet in the last few years, across a range of applications, the hegemony of the incandescent bulb has begun to flicker. Various lighting manufacturers, government agencies and utility companies are now working furiously at bringing us brighter alternatives. These parties are all taking different approaches to the task, and few of them proclaim so lofty a goal as bringing down the light bulb. Some of the groups -- such as the Pacific Northwest National Laboratory, which has sponsored innovative ways of persuading consumers to use efficient fluorescent lighting -- merely want people to start thinking about the inefficiency of incandescent bulbs the next time they're at the store.
Other agencies are looking for a more technologically sophisticated revolution in lighting. At government-sponsored labs like the Sandia National Laboratories in New Mexico, as well as at numerous private companies around the world, researchers are attempting to produce high-powered white LED lights that might transform the way we light the world. LEDs -- light-emitting diodes -- are made from semiconductors rather than tungsten filaments; they efficiently convert electricity into light through a process known as electron-hole recombination.
LEDs are far from uncommon in your average electronic gadget, but recently these lights have been edging their way into unexpected places -- traffic signals, concert stages, billboards, automobiles and, perhaps one day, a practical white-light lamp for your home.
Replacing incandescents with more efficient lighting will undoubtedly be good for the planet. According to researchers at the Sandia Labs, one-fifth of all the electricity produced in the world is used for lighting. Doubling the average efficiency of white-light lamps -- through LEDs or fluorescents -- could reduce global electricity consumption by 10 percent and carbon emissions by 200 million tons a year. It could make the whole world a brighter, lighter place.
If the recent history of lighting is any indication, few people will switch to new light sources simply out of a love for the environment.
"Most people, if you ask them if the environment is important to them, they'll say yes," notes Kelly Gordon, who runs Lighting for Tomorrow, a Department of Energy-sponsored program that aims to bring consumer-friendly fluorescent lights to the consumer market.
But people's affection for Edison's light bulbs can often run deeper than their affection for the earth, and convincing them to ditch incandescent bulbs requires an appeal to the bottom line, or to the eye, Gordon says. "You need to get in the messages about how it will save you money on your electricity bill -- and that it'll provide you very good light."
And this is where, for many consumers, the suspicion comes in. Can an alternative lamp ever produce good light as easily, reliably and warmly as a trusty old bulb?
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In the late 1990s, researchers at the Department of Energy became concerned that residential fluorescent light bulbs were floundering in the marketplace. Compact fluorescent lamps, or CFLs -- the name applied to the fluorescent bulbs that screw into standard lamp sockets -- are significantly more efficient than incandescent bulbs; for each watt of electricity they consume, fluorescents produce more light and less heat than standard bulbs, making a 27-watt fluorescent just as bright as a 100-watt incandescent bulb.
But the early compact fluorescents weren't very appealing. For one thing, they required a large initial investment -- even though they were often cheaper than incandescent bulbs in the long run, the fluorescent lights were selling in stores for more than $10 each, scaring people away. The lights also weren't very compact, making them not very pretty around the house. Plus, many of the compact fluorescent lights just didn't work very well. "They buzzed, they flickered, and they didn't last as long as they were advertised to last," says Linda Sandahl, a researcher at the Pacific Northwest National Laboratory. "The technology just wasn't there yet."
In order to spur innovation in efficient bulbs, Sandahl led a team at the lab that challenged lighting manufacturers to build a better fluorescent bulb. The lab asked companies to produce a very small CFL that didn't flicker and that carried a one-year warranty, all for a target price of $5 per bulb. In return, manufacturers would be connected to high-volume buyers, including some of the nation's largest utility companies, which would guarantee a market for the new bulbs. Sandahl says that several manufacturers responded to the challenge with innovative designs -- they created curious-looking bulbs in which the fluorescent tube was twisted, spiraled or folded near the base of the lamp, making for a significantly smaller light. A total of 17 different bulbs were created in response to Pacific Northwest National Laboratory's program, and the lab set up a Web site -- now called BetterBulbsDirect.com -- to channel the new lights from small manufacturers to large-volume buyers.
The program proved successful; the new, better CFLs entered the market just as the power crisis began to hit California, and utilities offered residents coupons and other incentives to purchase the new bulbs. Compact fluorescent lamps now represent around 3 percent of the residential lighting market, Sandahl says -- and in New York, California and the Pacific Northwest, they account for substantially more than that.
Despite their efficiency and improved performance, there is still a significant drawback to CFLs -- the light they produce is not as nice as the light from incandescents. Lighting designers use several methods to measure the "quality" of light sources, one of the most important of which is a light's color rendering index, or CRI. The CRI describes the light source's effect on colored objects; the higher a light's CRI, the truer the color of an object under that light.
By definition, a 100-watt incandescent light bulb has a CRI of 100, the highest possible measure, and one that's very close to the color rendering of natural daylight. Fluorescent lamps have low CRIs -- often in the 70-to-85 range. Another important measure of light is its "color temperature," a technical description of how "warm" or "cool" a light appears. Incandescent bulbs have a relatively low color temperature, the kind of comforting, orangish glow people like to have around the house. Newer CFLs can approximate this warmth, but fluorescents have traditionally produced harsher light, a "cold" illumination that offers little comfort.
So while compact fluorescent lights might be a valid alternative to incandescents in some applications -- who needs good color rendering in the bathroom? -- it's unlikely they'll become ubiquitous. "If you think about what makes good light, it depends on where you're using it," says Keith Scott, the business development manager of Lumileds, a Silicon Valley firm that manufacturers high-brightness LEDs.
"In your retail experiences," Scott says, "some of those big-box stores, you'll see fluorescents in the ceiling just spraying light all over the place -- and the lighting that comes down from there is adequate. But when you get into the shopping malls you see people using halogen lights to light clothing, because the halogen light is full spectrum -- you see all the colors. You rarely see people in fine restaurants eating under anything but incandescent or halogen light -- you want to see what your food looks like."
Lumileds is one of the dozens of companies looking to eventually produce what might be the holy grail in lighting -- a practical, efficient, high-quality white LED, something that might become a true replacement for Edison's bulb. There are many steps, and many hurdles, on the way to that goal, though, and for the moment the company is focusing on more conventional markets, one of which is traffic signaling.
A traditional traffic light is unabashedly inefficient, Scott says. "If you think about it, you're putting this 135-watt incandescent bulb behind this red or green or amber filter, and you end up only getting about 10 percent of the light out of there," he says. "You have to crank this monster up just get this small amount of light."
LEDs are monochromatic -- they can produce one color only, meaning that the light from them does not need to be colored by a filter. So a 135-watt bulb can be replaced with 6 or 12 watts of LEDs -- a huge savings. The LEDs also last longer than standard bulbs, so they save municipalities in long-term maintenance costs. For this reason, in large cities, Scott says, the transition to LED signaling is nearly complete -- drive through San Francisco and New York and many of the lights you'll see are powered by LEDs.
In general, Scott says, demand for high-brightness LEDs is currently concentrated in colored-lighting applications -- "lighting at clubs, discos, rock 'n' roll stages, to a lesser extent TV studios. Where we've seen the most success is in mobile stage lighting, like at theater shows and rock 'n' roll concerts."
At last year's Glastonbury Music Festival in England, LEDs were used in one of the 14 concert stages, Scott says. They were so successful there that, at this year's show, which takes place at the end of June, 11 of the stages, including the main stage, will use LEDs. Engineers aren't choosing these lights just because they're cheaper and more durable, but also because they allow for more creative flexibility.
"Because they're digital devices, you can do all the control digitally," Scott says. "What they're doing is they'll look at each light -- imagine this fixture containing red, green and blue LEDs -- and address each color to produce new and different colors. They'll create waves and washes of color onstage, things that are impossible with anything else."
So LEDs are good at color -- but what about white, natural-light LEDs? Because it's not until the LED takes the household light by storm that any appreciable impact on widespread residential electricity consumption will occur.
But that's a little trickier. So far, the only practical white LEDs that engineers have managed to produce is a kind of hack. To make an LED glow white, they coat a blue LED with a "yellow" phosphor -- a compound that absorbs part of the blue light and re-emits it as yellow light. The blue and the yellow light combine to form white, but it's not a very good white light, Scott says -- the light often has a very harsh temperature and poor color rendering. Lumileds has been able to improve on these measures; the company has developed a white light that uses yellow and red phosphors to produce a warm white light with a CRI of 93, making the light very similar to that of incandescents.
The trouble with the phosphor hack, though, is reduced efficiency. An incandescent bulb produces about 12 lumens -- a measure of light intensity -- per watt of electric power it consumes. A halogen bulb is about 15 to 17 lumens per watt. A "cool white" LED, the one that uses only a yellow phosphor, rates about 35 lumens per watt. But Lumileds' warm LED, which uses both yellow and red phosphors to produce a nicer light, produces only 22 to 25 lumens per watt -- more efficient than incandescents, but not really so overwhelming, especially when you consider that fluorescent lamps have lumen/watt measures in the 50-to-100 range.
Scott says that LED manufactures are working very hard to improve these numbers. "Today we're at 25 lumens, but we fully expect that to be well over 100 lumens per watt in time. What ends up happening when you get that high, you're not dissipating that much heat, and the possibilities become more exciting. Then we expect to see mass displacement of other markets."
How long will that take? A decade? Two decades? As with so many other things in technology, nobody can make an accurate prediction. Progress depends on many advances not yet made. LEDs are orders of magnitude more expensive than incandescent bulbs, and manufacturers will need to come up with creative ways to have them compete with standard bulbs. Eventually, though, LEDs will succeed; in time, say experts, they'll be able to produce white light better -- more cheaply and reliably -- than incandescents can, and at that time we'll probably all have to say goodbye to Edison's old light bulb.
But really, that won't be so bad. In the technology business, anything that lasts for more than a century has nothing to be ashamed of.