FIRST LED CITY: Torraca, Italy, is the first town to be entirely lit by LED lights.
Image: COURTESY OF CREE
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Torraca is a small village of 1,200 people in Italy. It is also the first place in the world to be totally illuminated by light-emitting diodes (LEDs). Representing a sea change, much like when electric lamps first graced London's Holborn Viaduct back in 1878, some 700 streetlights (each containing 54 LEDS) now line Torraca's arteries—and locales around the world, from Beijing's Bird's Nest Olympic Stadium to the Raleigh Convention Center's Shimmer Wall in North Carolina, have begun to use LEDs to light up the night.
"There are more than 30 installations like Torraca around the world," says Mark McClear, director of business development at Durham, N.C.-based LED-maker Cree, Inc., which made the LEDs in Torraca's streetlamps. "It's growing weekly."
The lightbulb of the future may just be a small piece of semiconductor. Rather than heating tungsten to at least 3,100 degrees Fahrenheit (1,700 degrees Celsius) or exciting fluorescent gases, LEDs can produce lumens with less electricity. Diodes are composed of two conductive materials, such as silicon or germanium; the light-emitting variety uses materials such as gallium arsenide, which releases photons when electricity flows through it.
Such LED technology has been in electronics like calculators for decades, but remains too expensive to replace cheap incandescents. An LED version of a 100-watt incandescent lightbulb, for instance, still costs roughly $80 compared with around $3 for a traditional incandescent.
Cost has been the major obstacle for LEDs, which last up to as 50,000 hours (10 years if used 12 hours a day)—gradually dimming over time—compared with about 800 hours for a typical 100-watt incandescent. "The average bulb is on two hours a day. At that rate, an LED would last 136 years," McClear says. "If you bought a fixture and only used it two hours a day, it would last longer than your house. It would last longer than you."
Potential energy savings, however, appear to hold more sway with cities and building owners than cost. After all, some 22 percent of all electricity use in the U.S. is devoted to lighting, according to the U.S. Department of Energy—and switching to LEDs could save $280 billion by 2028. In fact, researchers at the Rensselaer Polytechnic Institute in Troy, N.Y., estimate that replacing incandescents with LEDs could save $1.83 trillion in energy costs globally over the next decade and eliminate the need for 280 1,000-megawatt power plants.
"Forcing electricity though a filament and heating it up to the point where it emits light, [is] horribly inefficient, on the order of 95 percent inefficient," McClear says. "The best LEDs are on the order of 35 percent more efficient."
Among those dazzled by LEDs: North Carolina State University in Raleigh, which last year installed 730 Cree LED lights in a dormitory building and saved 44 percent of the energy consumed by the fluorescent predecessors per day, according to the university. Discount chain Wal-Mart has replaced fluorescent light fixtures in its freezer sections with LEDs. And the City of Los Angeles plans to replace some 140,000 street lamps with LED fixtures by 2014 at a cost of $57 million, tapping some of its funding from the Clinton Climate Initiative and the Los Angeles Department of Water & Power.
New LED lights can put out the equivalent light of 100-watt incandescent while only consuming 13 watts of power. They also outlast equivalent compact fluorescent lightbulbs but use 50 percent less energy and skip the toxic mercury required as ballast. The U.S. Environmental Protection Agency (EPA) estimates that 670 million such fluorescent lights end up in the trash yearly and release some two to four tons of mercury per annum into the environment.
Advances in the underlying technology have allowed Cree, for one, to boost output from a single one-square-millimeter diode to 161 lumens per watt. Partially as a result, the Federal Reserve is using LEDs for its overhead recessed lights and the Pentagon has installed some 4,200 LED fixtures to reduce energy costs and improve light quality, according to the U.S. Department of Defense.
Potential downsides: individual LEDs must be kept cool, and it may end up that the tiny fans in the multiple LED fixtures used to cool the lights will wear out long before the diodes. But manufacturers, including Brite Components, Cree, General Electric, Lighting Science Group, Osram and Philips say they are working to offset that problem.
Nevertheless, LEDs will not replace all lightbulbs, because they produce light in only one direction, like a laser, rather than illuminating an area. To fill that lighting need, some companies are creating organic LEDs, or OLEDs, that emit light in all directions and are already used in advanced televisions and other screens.
Such OLEDs—diodes made from organic material such as polyacetylene rather than semiconducting metals—may prove an even more intriguing future solution, because they can be crafted into ceiling panels or even windows (they are often translucent) and are potentially even more efficient at producing light (though not yet). BASF and Osram, for example, have achieved a white OLED capable of 60 lumens per watt. Others have achieved 100 lumens per watt in the laboratory, according to Barry Young, managing director of the OLED Association.
Unfortunately, such an OLED light panel at this point would cost at least $75 per square foot ($800 per square meter) and is not commercially available yet, Young says. But he believes the price tag can be significantly reduced by using plastic polymers and other cheap substances in lieu of glass. OLED lights are likely to become available as soon as 2011, according to a report from display consultants at the firm DisplaySearch in Austin, Tex. "It's likely to last longer [than LED fixtures] because it doesn't have anything to fail and it also doesn't have a lot of heat," Young says. "It won't generate the kind of heat that you would in an LED from the standpoint of air-conditioning."
But even Young believes that LEDs and OLEDs will likely coexist, serving different functions: LEDs will likely replace incandescents whereas OLEDs might light the offices of the future in the form of glowing ceiling panels or windows that light up as the sun sets. "It's happening faster than anybody thought it would or could," Cree's McClear says. "It doesn't make a lot of sense to do anything that's not green."
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21 Comments
Add CommentHopefully this trend will continue and more cities/organizations will continue to convert their lighting. While it might not make financial sense for some individuals to make the switch, it definitely makes sense for businesses and cities to make the change.
Reply | Report Abuse | Link to thisblog.benchside.com
I've seen LED Christmas lights. Too blue for my taste. Is anyone working on making them produce "warmer" light?
Reply | Report Abuse | Link to thisA few corrections, for the sake of accuracy:
Reply | Report Abuse | Link to this(1) Compact fluorescent light bulbs (CFL) contain mercury vapors inside the bulb, not in the ballast; rarefied mercury vapor emits in the ultraviolet (UV) range when excited by an arc discharge. The ballast is an electronic circuit which limits the discharge current once the current is established; (in reference to paragraph 9)
(2) See comment 1 above, the gas inside the CFL is not fluorescent; the UV light produced inside the gas (in fact, plasma), is absorbed by a special luminophore compound deposited on the inside wall the CFL's: through phosphorescence, the luminophore re-emits lower energy photons in the visible light wavelength range. (in reference to 3rd paragraph)
(3) Silicon and germanium, as well as GaAs, are more precisely semiconductors. They don't really release photons when electricity flows through (at least not in the visible light range); instead, visible light photons are released when opposite charge carriers from adjacent semiconductor blocks of opposite types, p and n, annihilate at the interface (junction). (again in reference to paragraph 3)
(4) The active material in organic LEDs is as much a semiconductor as the active material in inorganic, or regular, LEDs. Also, "semiconducting metals" is an oxymoron: metals are largely conductors, while semiconductors form a separate class of elements/materials (in reference to 2nd paragraph before last)
Further reading: [http://en.wikipedia.org/wiki/Luminophore] [http://en.wikipedia.org/wiki/OLED] [http://en.wikipedia.org/wiki/Semiconductor] [http://en.wikipedia.org/wiki/Compact_fluorescent_lamp]
Cheers
Its getting to the point where anything printed on this site has to be looked at very skeptically.
Reply | Report Abuse | Link to thisThere are more articles WITH mistakes than not.
This is not a good example of Science as it should be practiced.
Many LED companies now make full"warm white" LED's - 2700K.
Reply | Report Abuse | Link to thisJust got a tree full of them this year.
New LED's come in virtually any color of white from yellow-warm to blue-white.
Check out CREE.
I it's worse than you say 'zzzy'
Reply | Report Abuse | Link to thisThis article is full of rubbish. It's clear your are not actually an electrical engineer but your first two points are are absolutely correct.
I think the author of this article has slandered Cree semiconductors. I hope an editor reads this, as the article should be re-written.
A formal complaint needs to be made to SciAm - I might do this myself in the morning.
If you are interested in this kind of thing there are many quality textbooks on the subject lighting which is by no means the least interesting discipline in what I shall loosly term 'power electronics'.
W.J.Winkworth MIET
twinkle twinkle little star i want ot travel to the moon and go really far famous words from a poet william shakespear.
Reply | Report Abuse | Link to thisThis site, and Scientific American, is really going downhill.
Reply | Report Abuse | Link to thisThe "Science Daily" site really is much better:
http://www.sciencedaily.com/
SciAm is going downhill from what altitude?
Reply | Report Abuse | Link to thisI can understand some of the complaints, especially those concerning inaccuracies, but there are usually further references to more detailed accounts.
These are news flashes, and as such they serve a new purpose for SciAm. The quality can obviously be improved, but this applies to all providers of fresh news. I see two big advantages to the present setup. One is the provision of science news without the constraints of a print edition (esp a monthly one), and the other is the opportunity for readers to respond. This second advantage means that not only is the news fresh, but if there are any inaccuracies, alert readers are able to provide arguments and evidence to correct them ASAP.
It is a bit short-sighted of such valuable readers using a valuable service like this to complain about things that they themselves can rapidly deal with to improve the knowledge of all those readers lacking such specialized information, like most of us.
Where was such interaction between readers and science reporters available before the Net? Phone-ins? Lectures?
Why should readers have to check out reporters' facts by following the additional links in the report? What ever happened to Editors? Is it too much to ask for a report to be accurate? It's supposed to be 'science' writing, not an opinion rant. I agree with those who say SciAm editors are too involved in skeptics and anti-religion campaigns. They've missed 'real science' for years. If these articles are just trying to PUSH certain technology, instead of reporting the facts correctly, maybe it should go away.
Reply | Report Abuse | Link to thisSorry, readers! I forgot this forum is based in the US, where there are teams of reactionary and irrational Trolls with every kind of support, organized to whip up a feeding frenzy against science and progress.
Reply | Report Abuse | Link to thisToo bad the feeding consists of the usual straining at gnats and the cheerfully swallowing of big ugly camels.
I know an old woman
Who swallowed a camel --
Not any old mammal
But a big ugly camel...
She swallowed the camel
To eat a gnat,
Cos fancy that
She choked on the gnat --
What a crazy old bat!
1) The thrust of the item wasn't about the technicalities of lamp design, but about the proven benefits of one type of lighting technology in comparison with others;
2) A comment on technicalities was immediately seized on by other commenters to launch a barrage of unscientific attacks on the integrity, breadth and depth of the magazine's approach. No evidence, no attempt at proof, no logic. And a gratuitous insult to the thousands of scientists who have contributed to SciAm over the decades to present scientific issues in terms a layman can understand.
The bullies orchestrating a witch hunt might applaud this fetid slop, but no one else.
I rest my case.
I'll look over the corrections on this page for the sake of time. I did do a personal study (not in a controlled environment) on LED's vs incandescent lights bulbs. I have to say that my energy bill within the past 6 months have gone down by half. Me Gusta =) I refurnished my entire house with LEDs about two years ago. The initial cost was high, but I'm seeing returns in energy bills. The bulbs should pay for themselves by this years end. I called up www.LEDinsider.com (760-230-8045) and asked for a large sale discount and they gave me 15% off the entire order. They even took back some of the light bulbs that I didn't like. Buying into LEDs was the best investment I made before this recessions. Much better than all of my stocks that went down. At least I see some type of returns.
Reply | Report Abuse | Link to thisI'll look over the corrections on this page for the sake of time. I did do a personal study (not in a controlled environment) on LED's vs incandescent lights bulbs. I have to say that my energy bill within the past 6 months have gone down by half. Me Gusta =) I refurnished my entire house with LEDs about two years ago. The initial cost was high, but I'm seeing returns in energy bills. The bulbs should pay for themselves by this years end. I called up www.LEDinsider.com (760-230-8045) and asked for a large sale discount and they gave me 15% off the entire order. They even took back some of the light bulbs that I didn't like. Buying into LEDs was the best investment I made before this recessions. Much better than all of my stocks that went down. At least I see some type of returns.
Reply | Report Abuse | Link to thisI'll look over the corrections on this page for the sake of time. I did do a personal study (not in a controlled environment) on LED's vs incandescent lights bulbs. I have to say that my energy bill within the past 6 months have gone down by half. Me Gusta =) I refurnished my entire house with LEDs about two years ago. The initial cost was high, but I'm seeing returns in energy bills. The bulbs should pay for themselves by this years end. I called up www.LEDinsider.com (760-230-8045) and asked for a large sale discount and they gave me 15% off the entire order. They even took back some of the light bulbs that I didn't like. Buying into LEDs was the best investment I made before this recessions. Much better than all of my stocks that went down. At least I see some type of returns.
Reply | Report Abuse | Link to thisDid anyone mention that at the higher end of the "temperature" spectrum, Cree's (already kinda old and cold white) Q5 LED puts out at least 100 lumen per watt! It's rated 107-114 at .35 amp and 225 at 1 amp. It drops just over 3 volts (slightly more at the higher amperage like 3.5v). I can't believe they are so expensive (still) at between $5 and $10 each. These are perfect for solar lights as they use so little juice.
Reply | Report Abuse | Link to thisI thought the article was quite fine, didn't know about the oleds. Just thought that they should be reporting the most recent advances in lumen per watt lighting as comparisons. I'm sure that the highest efficiencies are with Cree's...
Reply | Report Abuse | Link to thisOk, after further searching...
Reply | Report Abuse | Link to this"Cree’s tests confirmed that the 1mm x 1mm LED produced 173 lumens of light output and achieved 161 lumens per watt efficacy at a color temperature of 4689K. The tests were conducted under standard LED test conditions at a drive current of 350mA, at room temperature."
WOW!
Ryan K could you please tell us which Led's you didn't like and sent back,and why you didn't like them.Thank you.
Reply | Report Abuse | Link to thisLEDs may be far more energy efficient but they're unsafe for human vision and health in general. They're rally only suitable for spaces in which people don't spend too much time.
Reply | Report Abuse | Link to thisWhat shocks me is how bright these led lights are. I've been shopping at a <a href="http://specialtyLightingAndBulbs.com">lighting store</a> for high efficiency items to help me out with my conservation efforts.
Reply | Report Abuse | Link to thisThank you for the correct interpretation of all the facts. My compliments ! Dr.Kamlander@aon.at
Reply | Report Abuse | Link to this