The incandescent lightbulb is a miracle of modern engineering. It requires a vacuum inside, blown glass and special filaments to work. Yet despite more than a century of refinements, an average bulb emits just 15 lumens of light for every watt of electricity it consumes. As a result, simple lighting accounts for 22 percent of the electricity used by buildings in the U.S. Now a team of engineers and chemists has created a carbon-based series of light-emitting diodes (LEDs) that operate at the pinnacle of efficiency while emitting a strong white light.
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