A Lightbulb Moment: The Old-Fashioned Filament


As a metaphor, the “lightbulb moment” doesn’t work so well now that we have to wait five minutes for a low-energy bulb to get going. But a group of researchers at the Massachusetts Institute of Technology (MIT) have had a bit of a lightbulb moment. The fondly remembered, but extremely inefficient, old-fashioned tungsten bulb could soon be modified to reuse its wasted energy. This would make it even more efficient than the new types of energy-saving LED and compact fluorescent bulbs to which we’ve switched in recent years.

Almost all the energy used by old filament bulbs is converted to heat, with only around 5% given off as light. In their paper, poetically entitled “resurrection of the incandescent source”, the MIT team describe how infrared radiation, which would otherwise be wasted, can be reflected and reabsorbed through a structure of up to 300 layers around the filament, using nanotechnology. “It is not so much the material you make the surrounding structure from, it is how you arrange the material to create the optical filtering property that will recycle infrared light and let the visible light through,” said Ognjen Ilic, from MIT’s research laboratory of electronics. This research could lead, one day, to the introduction of a high-tech lightbulb with an old-world glow.

The lightbulb, virtually unchanged since the 19th century, has become a target for climate-change campaigners in recent years. In the UK, it has been fiercely protected by those who view the EU – which ordered the phasing-out of incandescent bulbs – as a meddling force that wants us all to live in the cold, blue glow of low-energy lighting.

“It’s only a small thing, but people get intensely upset about it,” says Jonathan Wright, the owner of two lighting shops in south-east England and the purveyor of dwindling stocks of filament lightbulbs (“We strive to provide what the public wants regardless of European bans,” proudly proclaims its website). He sells lightbulbs under a loophole that allows the sale of “industrial” bulbs, which are essentially the same as domestic, but tougher and slightly more expensive. He says people travel miles to buy them. “People want them. The colour rendering is good, it’s soft. The fact they come on instantly.” Domestic users, he believes, have been unfairly penalised when other areas, such as street lights and office blocks that are lit all night long, should be looked at.

There is no other household essential that inspires the same level of affection as the humble lightbulb (see also the trend for oversized, exposed lightbulbs, as seen in every hipster coffee shop, which look as if they’ve been salvaged from Thomas Edison’s workshop). “Light is an emotional and emotive matter,” says the design critic Stephen Bayley. “I like it that [Henry David] Thoreau said candles illuminate darkness, but artificial light destroys it. Our affection for outlawed incandescent Edison bulbs is surely based on some lingering sense that the warm glow from a hot filament is closer to primitive candles than the chilly hiss and fizz of alien electrons.”

the guardian