What would it take to convince you to spend $45 on a 100-watt lightbulb?

A Silicon Valley company called Switch Lighting is banking that it has the answer. Switch is a start-up that plans to roll out a replacement for wasteful incandescent lightbulbs that is efficient, long-lived and attractive—whether lit or unlit.

Switch makes LED lightbulbs, a rapidly evolving technology that could well displace compact fluorescents (CFLs) as the energy-efficient bulb of choice. It is not the only company making LED bulbs, but may well be the first to produce a replacement for 100-watt incandescent bulbs, which impending U.S. regulations will essentially banish from store shelves after January 1. The law requires that bulbs produce the same light output of an old-style 100-watt bulb, as measured in lumens, on 72 watts or less. Switch and the other makers think consumers will prefer LEDs to CFLs, which many people snapped up for their widely-touted efficiency advantages over incandescents, only to find that the twisty, newfangled bulbs had some serious disadvantages as well.

Early CFLs gave off a sickly glow; they were incompatible with dimmer switches; they did not last nearly as long as manufacturers said they would. And, perhaps most damaging of all, consumers trying to go green were a bit miffed to find that CFLs contain a small amount of toxic mercury, meaning that disposing of the bulbs safely, or cleaning up a broken bulb, requires extra caution. Today's CFLs are far better than their early predecessors at mimicking the versatility and the warm glow of incandescent bulbs, but the mercury problem has not been solved.

Enter LEDs. The semiconductor-based bulbs already have a slight edge over CFLs in energy efficiency and are expected to become even more efficient in the coming years. (See a projection from the Department of Energy in the graph below.) They are dimmable; they contain no mercury.

Although manufacturers' claims need to be taken with a grain of salt, LED bulbs generally boast rated lifetimes two or three times as long as a comparable CFL, and 20 or 30 times as long as an incandescent. In short, an LED bulb is plug-and-play. It behaves much like a familiar incandescent bulb but lasts far longer and draws only one-fifth the electricity.

The performance specs of LED bulbs far exceed the impending U.S. regulations on lightbulb efficiency that will effectively do away with the manufacture or import of old-style incandescents, starting with 100-watt bulbs in 2012 and moving on to lower-output bulbs in 2013 and 2014. Companies such as Philips and Sylvania already have LED bulbs on store shelves to replace 40-, 60- and 75-watt incandescents. The newcomer Switch has not yet brought its products to market but says it will do so in 2012, including a replacement for 100-watt bulbs, the Switch100, which will retail for about $45.

The reason that Switch may be the first to produce an LED replacement for 100-watt bulbs is its innovative liquid cooling system that keeps the components from overheating. The glass dome of a Switch lightbulb is filled with a clear fluid that draws heat from the LEDs near the bottom of the bulb, circulates up to the top, and radiates heat through the glass before sinking again to siphon off more heat. Switch CEO Tracy Bilbrough, who paid a visit earlier this month to Scientific American's offices to show off his company's wares, likens the convective cooling cycle to a lava lamp.

Bilbrough would not reveal what the coolant is, but he says that it is a benign, food-grade substance that will be easy to reverse-engineer once the bulbs are on the market. "People will figure it out pretty quick," he says. The convective fluid, he says, gives Switch a roughly 30 percent cooling advantage over the air-cooled bulbs of his competitors. That allows Switch bulbs to produce more lumens from fewer LED chips—thereby cutting costs—because each chip can be driven harder without overheating. (The fluid also gives Switch bulbs significant heft; they each weigh about nine ounces.)

Whatever the manufacturer or cooling mechanism, an LED bulb's efficiency comes at a steep up-front cost. A single LED bulb currently costs about as much as 10 CFLs—or 100 incandescent bulbs. The cost of LEDs will come down, as they do for all semiconductor devices as those devices mature. And large, diversified companies such as Philips, which has a number of LEDs on the market, can afford to make the bulk of their profits from other products while LED prices ease down to more consumer-friendly levels.

But Switch is a single-minded company—it aims only to develop and sell LED lightbulbs. To survive, the company must convince shoppers that spending more money on a lightbulb now is a good investment in the long term.

In order for that to happen, consumers will have to change their view of lightbulbs, thinking of them not as an inexpensive, disposable product but as something that's likely to be around longer than the family dog. Switch claims its LED bulbs will last about 20,000 hours—that's more than 18 years if the bulb is on three hours a day, which is the usage assumed by the Federal Trade Commission in making bulb comparisons. Philips LEDs already on the market have advertised lifetimes of 25,000 hours, or more than 22 years.

In other words, if LEDs live up to their manufacturers' claims, a lightbulb installed in a child's nursery will still be around when that child finishes college. In the intervening years, most Americans will have moved several times. But Bilbrough expects that with the rise of pricier, more durable LEDs, people will start packing their lightbulbs up when they move, just as they do with small appliances nowadays. "I'm looking at this as a consumer durable," he says.

Mindset changes notwithstanding, Bilbrough says that his company will try to bring prices down to limit a shopper's initial investment. "We're obviously trying to reach price points where the consumer says, "'That makes a lot of sense to me,'" he notes. But even at today's prices, LEDs become cheaper than incandescents after just a few years of use. A 12-watt Philips LED (retail cost: about $25), for instance, produces as much light as a 60-watt incandescent (retail cost: about 40 cents). At an average U.S. electricity cost of 12 cents per kilowatt-hour, the LED bulb would save its owner $6.31 a year and would pay for itself in less than four years—during which time the same owner would have had to replace the incandescent bulb several times.

The economics of a 100-watt incandescent versus an LED will be similar, assuming that the production version of the Switch100 meets the company's current specs. Bilbrough says that the Switch100 ($45) will draw about 20 watts, which saves $10.51 a year on electricity when compared to an incandescent bulb (40 cents). Once again, the LED would pay for itself in about four years.

But the more established fluorescent bulbs are much cheaper, and LEDs cannot now compete with them on economics alone. LED manufacturers will have to count on the downsides of CFLs, in particular their issues with dimmer switches and their mercury content, spurring consumers to look toward other efficient alternatives. And Bilbrough hopes that the striking appearance of the Switch bulb, which graced the cover of WIRED in September and which recently won a design award, will help tip the scales as well. "You buy your laptop partly on its industrial design, you buy your cell phone based partly on its industrial design," he says. "Why wouldn't you care about how it looks?"