Teaching Old-School Light Bulbs a New Trick

By Nathaniel Scharping | January 12, 2016 3:28 pm

(Credit: Lukas Gojda/Shutterstock)

What was considered old technology, is new again.

Researchers from MIT took a counterintuitive step in the search for energy efficient illumination: Instead of devising a new means of lighting our living spaces, they resurrected the old, trusty incandescent light bulb. The old bulbs, much maligned for their relative inefficiency as compared to LEDs, were upgraded with new technology that captures and recycles wasted heat, potentially reaching efficiencies four times higher than LEDs.

What A Waste

Incandescent light bulbs, as we know them today, were invented in the 1880s by Thomas Edison and revolutionized our lives by emitting bright, steady light into homes and factories. Incandescent bulbs are constructed with a thin filament of tungsten wire surrounded by inert gas. When you flip a light switch, electrons are packed into a very small space, which heats the wire to around 4,600 degrees Fahrenheit and gives off light across the whole spectrum.

However, this process wastes most of the energy consumed in the form of heat, or infrared wavelengths. As a result, current incandescent bulbs achieve an efficiency of only 3 percent. Commercial LEDs, on the other hand, are roughly six times more efficient, making them the bulb of choice for energy-conscious consumers. But the tables may soon flip.

The MIT researchers created a kind of sheath for the glowing filament, called a photonic filter, composed of many layers of metal oxides. The molecules are arranged in such a way that only visible light escapes and wasted heat, or infrared light, is bounced back onto the filament where it is converted into light we can see.

Recycling Light

Writing in the journal Nature Nanotechnology, the researchers say their technology could yield light bulbs with efficiencies over three times higher than current LEDs. In addition, the photonic filter lets through light in the full spectrum of visible colors, which creates the warm glow that many consumers favor over the comparably harsher light produced by LEDs.

Their current prototype, still a proof-of-concept, is composed of 90 layers of silica and tantalum oxide. The researchers also created a new filament for the bulb by machining a flat strip of tungsten into an accordion-like shape that enhances the light bulb’s ability to reabsorb infrared light. Researchers say this bulb achieved 6.6 percent efficiency, already over twice as high as traditional incandescent bulbs. With different combinations of oxides and additional layers, the researchers say their concept could theoretically reach an efficiency of 40 percent.


The new and improved incandescent light bulb. (Credit: Ognjen Ilic)

The researchers see uses for their technology not only in light bulbs, but also in thermo-voltaic generators, which turn light into electricity. Capturing and reusing light could significantly boost the output of such devices. However, don’t expect to see these enhanced, incandescent bulbs hit store shelves anytime soon though. Following legislation that set efficiency standards for appliances in 2007, light bulb manufacturers shifted their focus to fluorescent bulbs and LEDs, leaving incandescent bulbs behind.

Still, there’s something to be said about curling up with a good book beneath the warm glow of an old-school incandescent.

CATEGORIZED UNDER: Technology, top posts
  • OWilson

    Heretiical blasphemy!

    But on the right side of history, so who cares?

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    “A hot mirror is a specialized dielectric mirror, a dichroic filter, often employed to protect optical systems by reflecting infrared light back into a light source, while allowing visible light to pass.” They were common in the 1970s. A four inch square hot mirror (Tiffen) will set you back about $400.

    Obama State of the Union addresses. “Never make promises the government can’t actually keep. Keep the promises already made”(2013). We don’t need no stinkin’ conservation!

    Converting sunlight into liquid fuel (2015)
    Create an “energy security trust.(2013)”
    Open more than 75 percent of offshore U.S. territory to drilling(2012).
    Go “all out” on every type of energy(2012)
    More nuclear power, more natural gas, more wind and solar(2011).
    Build a new generation of nuclear energy plants(2010).
    Double the supply of renewable energy within the next three years(2009).
    Lay down 1000s of miles of power lines to connect Americans’ homes to these new sources of energy(2009).
    Reduce Americans’ energy bills by “billions of dollars”(2009).

  • http://qpr.ca/blog alqpr

    From the opening paragraphs I thought that those MIT researchers had merely re-discovered my own technique – which “captures and recycles waste heat” from incandescent bulbs by using it to heat my home.

    Where I live, during 90% of the time the lights are on, this replaces heat that would have been provided by natural gas combustion with the carbon-free output of hydro-electric dams. But in its wisdom my government has chosen to deny me this option and to force me instead to use bulbs which take much more energy to manufacture and include dangerous pollutants such as mercury to poison the environment if I don’t dispose of them “correctly”.

    • OWilson

      But, but…. they mean well?

    • Maia

      Yeah, I do the same thing: when it’s cold, I use only incandescent bulbs and this keeps the temp up to comfortable usually without any further additions. You can still get incandescent bulbs in the form of “grow bulbs” or “full spectrum ” types, because plants (and eyes) MUCH prefer them. AND they don’t come with poison.

    • Milk Manson

      and they put that heat up at the ceiling, right where you need it.

      • http://qpr.ca/blog alqpr

        Unless you put all the lightbulbs on uninsulated outside walls and roofs, the heat will eventually redistribute itself throughout the building – even if it does so by first creating a temperature gradient. And in any case, it takes much less energy to redistribute heat than to create it.

  • Maryann Wood

    I need to be able to buy incandescent bulbs in the future. In winter I use 40 watt incandescent bulb for enclosed 8′ X 6′ X 2’crawl space opening from my cellar. Heat from the bulb keeps cold water pipes in exterior walls for the toilet and sink stay warm enough to prevent freezing. I need to replace the bulb about 3 times a season. Otherwise no fuss.

  • zloppolz

    “concept could theoretically reach an efficiency of 40 percent.”
    Long ways to go to match the 230% efficient LED.

  • Jeroi

    Just quoting this story. Incandescent bulbs 3% efficient. LED’s roughly 6 time more efficient= 18%. New incandescent possibly 40% efficient so that means incandescent could possible be roughly 2x more efficient than led.
    Where did you get 230%?

    • matthewkaney

      2 times something = 200% of something. so 230% is the same as say 2.3x. 2.3×18-41.4 so pretty close


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