The days of Edison's light bulb are numbered.
Take an LED that produces intense, blue light. Coat it with a thin layer of special microscopic beads called quantum dots. And you have what could become the successor to the venerable light bulb.
The resulting hybrid LED gives off a warm white light with a slightly yellow cast, similar to that of the incandescent lamp.
Until now quantum dots have been known primarily for their ability to produce a dozen different distinct colors of light simply by varying the size of the individual nanocrystals: a capability particularly suited to fluorescent labeling in biomedical applications. But chemists at Vanderbilt University discovered a way to make quantum dots spontaneously produce broad-spectrum white light. The report of their discovery, which happened by accident, appears in the communication "White-light Emission from Magic-Sized Cadmium Selenide Nanocrystals" published online October 18 by the Journal of the American Chemical Society.
In the last few years, LEDs (short for light emitting diodes) have begun replacing incandescent and fluorescent lights in a number of niche applications. Although these solid-state lights have been used for decades in consumer electronics, recent technological advances have allowed them to spread into areas like architectural lighting, traffic lights, flashlights and reading lights. Although they are considerably more expensive than ordinary lights, they are capable of producing about twice as much light per watt as incandescent bulbs; they last up to 50,000 hours or 50 times as long as a 60-watt bulb; and, they are very tough and hard to break. Because they are made in a fashion similar to computer chips, the cost of LEDs has been dropping steadily. The Department of Energy has estimated that LED lighting could reduce U.S. energy consumption for lighting by 29 percent by 2025, saving the nation's households about $125 million in the process.
Doesn't that amount of savings seem small? Does the United States really spend such a small amount of money on incandescent light electricity?
LEDs are more efficient because they do not emit in the infrared.
Of course, quantum dots, like white LEDs, have the advantage of not giving off large amounts of invisible infrared radiation unlike the light bulb. This invisible radiation produces large amounts of heat and largely accounts for the light bulb's low energy efficiency.
The breakthrough came accidentally and was the result of making quantum dots smaller than they are usually made.
Bowers works in the laboratory of Associate Professor of Chemistry Sandra Rosenthal. The accidental discovery was the result of the request of one of his coworkers, post-doctoral student and electron microscopist James McBride, who is interested in the way in which quantum dots grow. He thought that the structure of small-sized dots might provide him with new insights into the growth process, so he asked Bowers to make him a batch of small-sized quantum dots that he could study.
"I made him a batch and he came back to me and asked if I could make them any smaller," says Bowers. So he made a second batch of even smaller nanocrystals. But once again, McBride asked him for something smaller. So Bowers made a batch of the smallest quantum dots he knew how to make. It turns out that these were crystals of cadmium and selenium that contain either 33 or 34 pairs of atoms, which happens to be a "magic size" that the crystals form preferentially. As a result, the magic-sized quantum dots were relatively easy to make even though they are less than half the size of normal quantum dots.
After Bowers cleaned up the batch, he pumped a solution containing the nanocrystals into a small glass cell and illuminated it with a laser. "I was surprised when a white glow covered the table," Bowers says. "I expected the quantum dots to emit blue light, but instead they gave off a beautiful white glow."
"The exciting thing about this is that it is a nano-nanoscience phenomenon," Rosenthal comments. In the larger nanocrystals, which produce light in narrow spectral bands, the light originates in the center of the crystal. But, as the size of the crystal shrinks down to the magic size, the light emission region appears to move to the surface of the crystal and broadens out into a full spectrum.
As all matter of materials get made at smaller sizes more interesting, unexpected, and useful behaviors of materials will be found.
By Randall Parker at 2005 October 25 10:54 AM Energy Tech | TrackBackAssuming 110 million households, consuming 940 kwh/yr, at electricity prices of $0.08/kwh total lighting electricity costs should be ~$8 billion.
http://www.eia.doe.gov/emeu/reps/enduse/er01_us.html
U.S. HOUSEHOLD ELECTRICITY CONSUMPTION IN 2001
Electricity consumption by 107 million U.S. households in 2001 totaled 1,140 billion kWh. The most significant end uses were central air-conditioning and refrigerators, each of which accounted for about 14 percent of the U.S. total.
In 2001, lighting accounted for 101 billion kWh (8.8 percent) of U.S. household electricity use.
http://www.eia.doe.gov/cneaf/electricity/page/fact_sheets/retailprice.html
In 1999, industrial customers paid an average 4.43 cents per kilowatthour (kWh), while residential and commercial customers paid an average 8.16 cents per kWh and 7.26 cents per kWh, respectively.
If we assume that a certain fraction of our airconditioning use merely compensates for the waste heat generated by conventional lighting, then we can expect this new form of lighting could lower our energy consumption that much more.
If american consumers start to demand efficient lighting and appliances, the movement will build some momentum. The american consumer drives the entire world economy. Change the buying habits of the american consumer and you can control the world.
"capable of producing about twice as much light per watt as incandescent bulbs"
Hmm? I thought the energy usage was half of flourescent lights? I pay utilities on all my apartment units and with electric running around 12.48 cents per kwh here I install compact flourescents in all fixtures. I've done that for over eight years now even when the bulbs were over $10 each. Currently they sell for around $2.50 each, have good spectrum output and use about 1/4 the energy of an incandescent bulb of equivalent light output. Admittedly the Chinese made (read Chinese prison produced) versions have a higher failure rate but it's acceptable as of this time.
If the acticle is fully accurate then it's not gonna happen. To expensive to buy or operate.
memochan - I've seen back-of-the-envelope estimates that U.S. business spends about the same amount lighting and then cooling the heat from the lighting.
A great deal of lighting is from already efficient flourescents. A great deal of the electricity doesn't go to lighting.
For those interesting in LEDs now, This is probably the best deal on the net as far as candellas for cost, while not needing thousands of LEDs to light a room... just maybe hundreds :)
http://www.lsdiodes.com/shop/index.php?main_page=product_info&cPath=1&products_id=19
I'm working on a project that requires very many of them. The point isn't efficiency, but aesthetics of many tiny point-sources of light.
Carl,
Thanks for digging up that information. Yes, that is more what I'd expect. The savings would range into the billions.
What part of the year does the average house in America need cooling versus heating? The trend is toward migration to warmer climates. So probably an increasing amount of light bulb heat goes toward battling air conditioners. But some of the heat goes toward heating homes in winter. Granted, eletricty is an expensive awy to heat a structure. But the savings from electricity reduction is partially offset by greater heating needs in cooler times of the year.
Joseph,
My guess is that the vast majority of houses have incandescent lights. I use incandescents inside because I really dislike flourescent light. I use flourescents outside though.
Given that LED's naturally work off DC, this means LED lighting will be even more efficient with electricity from solar or stored in batteries.
Right now, LEDs are still too expensive; broad-spectrum fluorescent is quite a bit cheaper and nearly as efficient.
IIRC, quantum dots can also be excited directly by electricity. Eliminating the LED as the middleman would boost efficiency quite a bit. Arranging quantum dots in a circuit could be tricky, but so much has been done with precision placement of molecule-scale things using DNA strands that something of the sort might do for light emitters. Make a "circuit board" with molecular tags to tell the DNA where to latch on, dip it in a bath of DNA strands with quantum dots on them, and voila.
I swear I've read that fluorescents are linked to depression. The light they also give off is hideous. The quicker they are gone from the marketplace, the better.
It all depends on the mix of phosphors, Mariana. Early fluorescents did a lousy job of emulating sunlight.
From the perspective of energy savings in cold climates, maybe gas lights would be best? 100% of the energy would be useful as heat, and would contribute some much needed humidity as well. I'm sure there's some high tech answer to the old problem of leaks.
Current flourescent lights have a very good spectrum output. In particulare the compact (quite a bit of familiarity with them) have greatly improved. Example the newer 90 watt equivalents (23 watt consumption) have a very good appearance and are vastly superior to the versions of only a few years ago when set side by side.
Now the heating effect from lighting devices is actually wasted in most cases. Normally such lights are at/near the cieling and basically just heat the cieling itself unless you're using some type of air circulation device (i.e. cieling fan). In the case of recessed lighting it's even worse since they're normally vented by code up through the cieling to prevent heat build up and possible fire hazards.
Ideally heating systems would become electrically based in the future. Generation III or IV nuclear plants should have noticeably lower operational costs. Wind farms might even become practical some day for adding to baseload. Hell who knows maybe someday fusion might become practical (not betting on the tokamac but the levitated dipole concept looks very interesting).
Those nanovoltaics would go far if they were hooked up to cheap fiber optic cables. When the sun is bright enough solar collectors would circulate light alongside the ceilings in the manner of fluorescent bulbs. Light switches could even specify how and along what cables light is directed. When the sun is off, a nanolight is on, one bulb doing the work of about 4 in different areas of a household or office.. The fiber optics can be connected to drop-ceiling tiles by non-electricians, the nanobulb can be configured into a fairly conventional ballast. But the solar collector is a problem. People for some reason have a great reluctance to punching a hole in the roof, even to shine light or let in air. Idiotic, when you think how many building owners let their roofs go to hell by not re-asphalting, or replacing shingles. It is very bad to let the utility company handle an"energy saving" program to replace old fluorescents with new ones, when solar-based solutions like the one I describe here can really cut rather than stabilize utility consumption.
One number I’ve seen is that 16% of all US electricity consumption is for lighting. That $125 million number looks awfully small, by at least one order of magnitude.
Perhaps the higher initial cost of the lamps offsets the energy savings?
Tim: You're right to question that.
Net electric generation in 2004 was 3.9534 trillion kWh. 16% of that is 633 billion kWh. If we assume 5¢/kWh, that is worth 31.6 billion dollars. If 25% of lighting goes into incandescents and we can save 70% of that by conversion to fluorescent and LED, we would save $5.5 billion dollars a year or almost $19 per capita per year.
I re-lamped my dwelling years ago. My most-used lights are a circle-tube 3-way CF in a table lamp and a twist-tube CF in a desk lamp (used for indirect light). My typical lighting demand is satisfied with less than 50 watts.
The error several posters have made is confusing lighting demand with total demand. Commercial and Industrial customers use power to run machines, so the new lighting technology would not help much.
Even with residential customers (about 33% of users), lighting is a small percentage of total consumption—for example, most electric dryers run on a 22C, 30 amp circuit. Allowing a 25% margin of safety, that’s about 5000 watts/hour. Most electric light bulbs are below 250 watts, so that’s 20 hours of lighting = 1 hour dryer usage. Electric ovens are also juice hogs.
A 2500 square foot house needs about 60,000 btu’s/hour of A/C (rough swag, depends on a number of factors), assuming a 10.0 SEER rating, (the current Federal minimum “new and clean”, though older, poorly maintained units are less) is 6 kW/hour, or 24 hours of a 250 watt bulb = 1 hour of A/C run time. Run times vary by geography, but, for example, A/C’s in San Antonio are assumed to run 2200 hours/year.
John Galt,
I do not see anyone making the mistake you claim of confusing total and lighting electric demand. The posters do understand that lighting accounts for only a percentage of total electric usage and people above produced a couple of different referenced sources for what percentage that is for total electric consumption. The very first comment from Carl cites a source for lighting accounting for 8.8% of total home electric usage in 2002.
By contrast, you do not provide an estimate for what percentage light is of total residential usage.
What we do not know is what percentage of current residential or business lighting usage is still incandescent. E-P makes a probably low guess estimate of 25% for residential. He still comes up with a large potential savings from a shift to LED or flourescent.
John Galt also uses the term "watts/hour" where it isn't applicable. Hint: if you see anyone using it at all, they're almost certainly using it erroneously. Watts are power and watt-hours are energy; if you catch yourself writing "watts/hour" slap yourself on the hand and just write "watts".
when will this be available?? I did see an LED grill light for sale on net, for use on patio. But looks like it could also be used as a clamp on desk light. In general, it seems that the down side of LED is that although LED can BE SEEN from a great distance, there is NOT much actual LUMINOSITY in the immediate area surrounding it. I mean, it wont light up a room, but yet you can see its point of light from across the street.
We spend the greater part of our lives working in offices and factories that use cheap or inadequate lighting. A friend of mine who has her
business in an old warehouse, was recently visited by a Salesman who represented a company called Maintenance Engineering. Well, her business
is called "Working Artists" and the name speaks for itself. Art projects, an art gallery and art classes are featured here. She was sick and
tired of old fashioned fluorescent lights and short life incandescents and the impact that they had on her art work. The salesman from Maintenance
Engineering took down two of her fluorescent lights and replaced them with two of his. The difference was astounding! All she could say was WOW!
Can you imagine what poor lighting does to the morale of the average office worker - especially those folks who work in windowless offices? It must
be devasting. I just read something about SAD and I was shocked. If you happen to be one of thoser who works in an office and wonders why you're depressed and more prone to illness during the winter months, Say something to your boss about Maintenance Engineering. They might just hold the key to end the suffering that people at work go through, when the sun doesn't shine. Since regular fluoresecent lighting, spot lights and incandescent lights purchased at your local store are not full spectrum and they don't seem to last very long in commercial or industrial applications, Lighting purchased from those guys at Maintenance Engineering may be the answer to SAD and also provide businesses with savings on their bulbs!
The real problem with LED lighting is directionality. They are very focused. Filamentary and phosphorescent (fluorescent, mostly) put out light in many directions. They are practially omnidirectional. This is good for many uses. The omindirectional aspect is especially good in table lamps. It is less desirable in ceiling fixtures but still beats a tight beam.
Designs can be produced to overcome this but there are many limitations with LED lighting. There is still the heat problem. The only commercially viable (well, sorta, at $90) incandescant replacement is not usable in an enclosed fixture so it will not be usable in ceiling lights. It is also a large, finned design and not reasonable for usage in most uses due to aesthetic reasons.
So there is still quite some room for improvement in several areas before LED lighting will make a significant impact in the marketplace: cost, looks, beam of light, heat. Buy stock in a company but have some other stock to keep you in funds until it takes off.
I saw the ad earlier about the wonderful flourescent lights your friend bought with Maintenance Engineering and I am a sales rep for them. IF anyone in NC is interested in a free demo of this wonderful flourescent lighting give me a call. These light bulbs are about as close to natural sunlight that you can get. They are wonderful. On top of that the warranty for most of the flourescents are around 5 years.... YES 5 whole years.
If interested call me Julie and I will tell you more. 336-549-7244
The number is 125 Billion / not million... that is a typo.
Fox News video link is midway down on this page and quotes the estimated cost savings:
I am also an Maintenance Engineering sales rep. From Indiana and if you would like a demonstration email me at rday7@sbcglobal.net
Hey, what do ya know? I also work for Maintenance Engineering and am located in upstate South Carolina. Just goes to show that we have sales reps all over the U.S. If anybody in upstate S.C. is interested in a free demo, just like what my other associates on this website are offering, then call me direct at 864-384-4910 and ask for Shan Kelley. This is absolutely amazing lighting for any application and can make a huge difference not only in appearance but overall attitude and can actually increase productivity because it is so close to natural sunlight. You can visit our website at me-dtc.com to find out more about your application, our lighting, and our company. Then call me, and I'll show you for free.
I am also a rep for Maintenance Engineering. I can tell you dozens of stories like the one above. If you would like to see a free demonstration in your own fixture in or around Utah please let me know.
Jon Burridge
801-446-0142
melightbulbs@yahoo.com
Well what do you know, seems that there are quite a few Maintenance Engineering (ME) reps checking out this site. ME offers a full line of premium quality lighting products, however ME's fluorescent lamps are the pride and glory. ME's fluorescent lamps have light quality and spectrum that matches natural sunshine AND our tube lamps are guaranteed in writing to last 60 months (18 times longer than a standard incandescent)!
See what a differnce better lighting can do.
Contact me for a free, no obligation demo:
Jonathan Lam
Energy SaverZ Lighting
Dewey, AZ
602-324-7254
lightbulbs@cableone.net
Hi, there are several of you from Maintenance Engineering (ME). Just yesterday I interviewed with them for a position in the Northeast. This seems like a great opportunity but my concern is having to pay money up front to start. Does anyone have any comments on the opportunity. how long you've doing it, if you're making enough money to live? Any advise regarding the opportunity would be much appreciated.
My email is jgianino@comcast.net
Thanks
Hi, like Jim I am considering ME and just spoke to them today. I am concerned about any opportunity that asks for $$ up front, but doing research so far I have seen nothing that would indicate this is a scam. However, I would like any input as to whether this is as good an opportunity as they make it out. I am not afraid of hard work and have been in sales for 10 years, but can you really make a good living selling lighting?
any feedback would be helpful.
John \
windhm@yahoo.com
Thanks