An energy-saving light bulb containing LEDs uses up to 80% less energy and lasts up to 25 times as long as a traditional incandescent bulb. There’s just one problem: many people think that the quality of light coming from an LED bulb feels less natural. A new innovation from MIT might help consumers get the best of both worlds, bringing the incandescent bulb closer in line with the energy efficiency of LED lights while maintaining its homey glow.
Incandescent bulbs work by using electricity to heat up a thin tungsten filament–that little hair of metal you see inside every bulb–to more than 5,000 degrees Fahrenheit. The problem with this approach is that most of that electricity is wasted as heat, which is why a 60 watt incandescent light bulb emits the same amount of light as a 12 watt LED. LEDs, on the other hand, don’t use filaments at all. They directly translate electricity into light by moving electrons through a transistor, essentially cutting out the middleman.
So how do you make an incandescent bulb as efficient as an LED? Basically, you bounce the wasted heat back at the filament, so it stays hotter with less electricity. MIT’s design uses photonic crystals to reflect heat-carrying infrared light back at the filament, while allowing visible light through. MIT’s design uses 90 layers of these crystals to cut down on waste, while also boasting a special folded filament which has been designed from the ground-up to optimally absorb infrared light.
While not ready for retail yet, MIT’s new incandescent technology triples the efficiency of a normal incandescent bulb… and the team thinks it might still be able to eke another 40% efficiency from the design with some tinkering. That could be enough to make incandescent bulbs popular again, at least when it comes to energy efficiency. One aspect of LEDs remain unmatched, though: their extreme longevity compared to incandescent bulbs (thin metal filaments heated to 5,000 degrees tend to have short life expectancies). If MIT has solved the life expectancy problem of incandescents, it’s not saying so.
You can read MIT’s paper on their new approach to incandescent bulbs here.