Science Purdue LED Us to More Efficient Lighting, Less Mercury
posted by July 21 at 15:19 PMon
Longtime readers know of my aversion to compact fluorescent lightbulbs:
The “mercury vapor” that fluorescent bulbs require is quite toxic. While new compact fluorescent bulbs are voluntarily limited to five milligrams of mercury each, as little as a tenth of a milligram per square yard will make you seriously ill. Shaking hands, drooling, irritability, memory loss, depression, weakness—sounds like fun. And that’s what happens to adults; kids can be permanently injured by mercury exposure. If you break one of these bulbs in your house—and think of all the times a bulb breaks—the current advice is to open a window and run, not to return for at least 15 minutes. Whereas if it’s a traditional bulb, you grab a broom and screw in a new one.
And even if you manage to not accidentally dump hazardous waste in your living room, what do you do with a fluorescent bulb when it just plain wears out? Most places cannot recycle fluorescent tubes.
There is another. LED (light emitting diodes) have a similar energy efficiency to fluorescent bulbs with a far friendlier environmental impact. In the least, they involve no mercury.
Great! Why not use them everywhere? Huge expense. Most LEDs are based upon a substrate of sapphire. Urk. Requiring a precious stone means LED lightbulbs are about twenty times more expensive than traditional lightbulbs.
Enter some clever researchers at Purdue University:
The Purdue researchers have solved this problem by developing a technique to create LEDs on low-cost, metal-coated silicon wafers, said Mark H. Oliver, a graduate student in materials engineering who is working with Sands.
(Who would think something good could come from Indiana?)
Replacing the sapphire with silicon (made from sand) makes the bulbs fantastically cheaper. Good work people. Expect the cheaper, environmentally sound and energy efficient bulbs in stores in about two years.