The End Of The Light Bulb?

sdmonroe wrote to mention an MSNBC article discussing the likely eventual replacement of common light bulbs by LEDs. That replacement is likely to come quicker thanks to an accidental discovery announced this week. From the article: "Michael Bowers, a graduate student at Vanderbilt University, was just trying to make really small quantum dots, which are crystals generally only a few nanometers big. ... When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color. But when Bowers shined a laser on his batch of dots, something unexpected happened. 'I was surprised when a white glow covered the table,' Bowers said. 'The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.'"

Comments

As a lighting design student...

[maino82]

I can definitely see the benefits of LEDs when compared to other forms of electric light. They do produce more lumens per watt than most other sources, but they do produce a good deal of heat when combined together into a large array, despite what people may tell you. They also have the added benefit of efficiently producing (since they only produce light in a certain wavelength) just about any color you would want through color mixing of different color LEDs (check out the tunnel in the Detroit airport if you'd like to see a well done example). Personally, though, I would love to see more daylight in spaces rather than a push for the latest and greatest in electric light. If done properly, daylighting can greatly increase light levels in the workplace and lower energy consumed by electric light. Generally, this will lead to an increase in cooling load, but this is almost always smaller than the amount of energy saved by eliminating electric lighting (again, if done properly). So while I'm all for more efficient electric lighting, it would be nice to see no electric lighting used during daylight hours when the sun is readily available.

Re:Not sure this discovery is necessary

[SuperBanana]

The only thing holding them back is price.

No- many things are holding back LEDs.

• They produce light efficiently (not THAT efficiently) but don't produce that much light compared to a very simple single-bulb HID or fluorescent tube (by the way, which tube are you basing that "3x" on? T12, T10, or T8? Because T8's are MUCH more efficient that T12's). It takes a HUGE number of LEDs to replace ONE T8 fluorescent tube- and that tube costs a few dollars tops, because it is very easy to make. Right now, a single Luxeon white LED sells in 100-1000 unit quantities for well over $10-20, and produces 1-5W. A T8 bulb will produce 30-40W, and costs RETAIL about $5.
• They require new reflector designs and light spreaders, since they are a VERY small point source. A lot of work goes into making light sources produce even, smooth lighting that won't generate harsh shadows- point sources make this job a real bitch. Point source also means that despite relatively low heat output the heat is very localized, and that means PCBs must also be heat spreaders, complicating assembly/design/manufacture further. You can't just toss them on a PCB. Companies like Luxeon now sell them on little PCBs with the necessary spreader etc, but now you're not just talking about buying an LED, you're buying a whole assembly for your product...$$$.
• Related- while they have a long life before failure, most of the high-output LEDs drop in light output very significantly, within a year or two of continuous operation 10-20 degrees above room temperature. VERY few LED manufacturers disclose this upfront- and virtually ALL the companies hawking LED products fail to mention this nice little caveat. Furthermore, just because the LED is rated to, say, 100,000 hours- doesn't mean it won't burn out because the company that made the device it is part of didn't botch the job on current+voltage regulation, heat dissipation, etc.

I know everyone thinks they are the second coming of Christ, and they do have some wonderful applications (like traffic signals and car brake lights)...but they're not the end-all be-all.