Photo of a proof-of-concept device that already achieves efficiency comparable to some compact fluorescent and LED bulbs

Traditional bulbs get massive efficiency boost

Incandescent light bulbs could return to homes after researchers found a technique said to make them more than twice as efficient as even the best LED bulbs.

The original bulb technology was largely phased out in Europe starting in 2007 on environmental grounds because they are only two to three per cent efficient, with most of the energy lost as heat.

Traditional bulbs compare poorly to fluorescents, which have an average efficiency between seven and 13 percent, and LED bulbs which are typically between five and 13 percent efficient.

However, a team at the Massachusetts Institute of Technology (MIT) has found a way to reabsorb the heat energy from incandescents which allows them to reach efficiencies as high as 40 per cent.

While waste heat normally dissipates away from the bulb in the form of infrared radiation, the team added secondary structures that surround the filament to recapture the radiation and reflect it back to be re-absorbed and re-emitted as visible light.

The structures, a form of photonic crystal, are made of elements that are abundant on Earth and can be made using conventional material-deposition technology.

Although the first proof-of-concept units are currently only achieving about 6.6 per cent efficiency, the team notes that they are already a threefold improvement over the efficiency of today's incandescents and believe this can be boosted with further research.

"LEDs are great things, and people should be buying them," said MIT professor Marin Soljac. But "understanding these basic properties" about the way light, heat, and matter interact and how the light's energy can be more efficiently harnessed "is very important to a wide variety of things," he added.

“The ability to control thermal emissions is very important. That's the real contribution of this work."

And as for exactly which other practical applications are most likely to make use of this basic new technology: "It's too early to say."

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