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I've always admired incandescent light bulbs, and find it
amazing that an electrified wire filament could hold a near-monopoly on
commercial electric lighting for a century or so. Since the mid-1990s, though,
many different lighting technologies have sprouted up, all vying to succeed the
trusty Edison bulb.
The incandescent bulb's drawbacks are well known. To begin
with, their luminous efficacy-the basic measure of how efficiently they produce
light, in lumens per watt-in a word, sucks. A 40 W bulb has a luminous efficacy
of about 12.6 lm/W for an overall efficiency of 1.8%. If that sub-2% figure
doesn't sound terrible enough, it's only a little under 50 times brighter than
a candle. Incandescent bulbs convert most of their energy into heat, which is
wasteful unless you're using one to heat a terrarium or power an Easy-Bake
Oven. This poor performance and new pushes toward energy efficiency have led governments
worldwide to order phase-outs or bans on incandescent bulbs.
Swirly CFL bulbs have grown in popularity and dropped in
cost, and they're roughly 3-5 times more efficient than traditional incandescents.
LED bulbs are about the same efficiency-wise, although research
points to a pretty high ceiling as far as possible luminous efficacy.
More recently, lighting researchers have begun experimenting
with the celebrated supermaterial graphene. A graphene-coated LED bulb
co-developed by the University of Manchester and its spin-off company Graphene
Lighting PLC, both in the UK, will likely go commercial later this year. While
the university claims the lamps will be "competitively priced" and manufactured
using sustainable components, there's been no mention of a more precise retail
cost. It's also worth noting that last month Canadian
investors Oriana Resources Corp. signed papers to acquire Graphene Lighting PLC. How this will affect lamp production remains to be
seen.
In June, researchers from Columbia University and two Korean
organizations announced that they'd jointly developed an on-chip light source
using a suspended graphene filament. The device requires little power to heat
up to the point of emitting visible light, in this case around 2500° C, and
despite being only one atom thick, the graphene strip emitted light visible to
the naked eye. While the
press release hints that the team's more interested in the lamp's potential
heating abilities, it could be useful in transparent displays and optical
communications. And in an ironic twist apparently not lost on the research team, graphene is derived from carbon-the same filament material used in
Edison's original incandescent bulb.
Despite its history of fearmongering, the so-called US
"light bulb ban" only applies to the manufacture of 40- and 60-watt
incandescents that don't meet certain brightness standards and efficiency
ratings, and there are plenty of other options as far as wattage and bulb type.
Still, a select few manufacturers have
been producing and marketing "rough service"
bulbs that legally buck the US ban on general service bulb production. At most
retailers these "newcandescent" bulbs carry a steep price tag (over $5 per
bulb), so you're probably better off biting the bullet and getting the cheaper
CFLs anyway.
As the era of incandescent bulbs winds down, it seems we're
only certain of the fact that the dominant lamp of the future is still unknown.
Image credit: Vinovin/CC BY 2.0
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