Incandescent lightbulbs are dead. Or at least they were supposed to be. Dozens of nations have vowed to phase out the old-fashioned, inefficient bulbs that pushed electricity through a sliver or tungsten filament and heating it up to 2,700 degrees Celcius, while wasting about 95 percent of the energy they created.
The U.S. has gone back and forth about tossing the more than century-old incandescents on the trash heap of technology in favor of compact florescent (CFL) and light-emitting diode (LED) bulbs, in part because a lot of people don't like the light created by the more-effienct alternatives and don't want to spend way more on the new ones. But now a group of scientists at MIT and Purdue University think they may have found a way to keep the incandescent alive.
According to a report on their work, the key to reviving incandescents rests on two key factors: sticking with the traditional heated metal filament and using a series of "nano mirrors" to collect the infrared radiation created from warming them up and reflecting it "back to the filament to be re-absorbed and re-emitted as visible light."
Let's repeat that one bit: NANO MIRRORS!
Actually, they call them "photonics crystals" -- made up of 90 ultra-thin layers of tantalum oxide and silicon dioxide -- which both reflect some wavelengths of light while allowing some to pass through. They also replaced the traditional curlycue tungsten element with a tungsten ribbon folded over itself that offers more surface for the electrons to strike and heat up the element, letting it absorb more infrared photons as they bounce off the crystals.
The researchers said their new bulb nearly doubles the amount of "luminous efficiency," a measure of how efficiently the lighting system converts electricity to light. Typical incandescents have a luminous efficiency of 2-3 percent (CFLs are around 7-15 percent and LEDs are 5-15 percent.) But this new "two-stage" incandescent the MIT team is working on could raise efficiency up to 40 percent.
Now, keep in mind, the test set of bulbs they've made have only gotten to around 6.6 percent efficiency, which is close to the current level of CFLs and LEDs, but that's already a huge improvement over current incandescents.
One of the lead MIT researchers, postdoc student Ognjen Ilic, said what they're doing is "light recycling," since their new material "takes in the unwanted, useless wavelengths of energy and converts them into the visible light wavelengths that are desired," reusing energy that would otherwise be wasted.
The bulbs are not close to being available at your local Home Depot just yet, but considering that lighting eats up 11% of all electricity in the U.S., it could make a big impact on our carbon emissions.