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Power Technology

DOE Shines $21M on Advanced Lighting Research 238

Posted by ScuttleMonkey
from the bright-ideas dept.
coondoggie writes to mention that the US Department of Energy is planning to fork over close to $21 million for 13 projects promising to advance solid-state lighting research and development. "SSL lighting is an advanced technology that creates light with considerably less heat than incandescent and fluorescent lamps, allowing for increased energy efficiency. Unlike incandescent and fluorescent bulbs, SSL uses a semi-conducting material to convert electricity directly into light, which maximizes the light's energy efficiency, the DOE said in a release. Solid-state lighting encompasses a variety of light-producing semi-conductor devices, including light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). "
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DOE Shines $21M on Advanced Lighting Research

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  • by GregPK (991973) on Wednesday February 13, 2008 @04:41PM (#22410934)
    The best flourescent out there gets roughly 70 lumens per watt. LED's have already passed the 100 lumens per watt barrier.
  • What rubbish (Score:5, Informative)

    by EmbeddedJanitor (597831) on Wednesday February 13, 2008 @04:44PM (#22410990)
    LEDs are far more efficient than incandescent. I have an LED/incandescent flashlight that lasts far longer in LED mode than incandescent mode but is not quite as bright. ie. Led brightness * LED time far greater than incandescent brightness * incandescent time.
  • by Anonymous Coward on Wednesday February 13, 2008 @04:47PM (#22411048)

    Where do I buy them now

    EarthLED Light Bulbs [thinkgeek.com] which are more efficient, last longer, use less energy, and are greener to produce than even CFLs (which are greener than incans).

    Do they fit...

    Yes!

    ... as much ... light?

    Yes! I own two (would own more but see price). etc. etc. Read the page, it answers your questions. They are dimmable, etc. etc.

  • by Anonymous Coward on Wednesday February 13, 2008 @04:53PM (#22411110)
    There's even studies that show a lot of lighting does NOT deter crime. All it does is let the crook see what he's doing.

    The studies I saw were about all street lighting. Street lighting creates plenty of shadows near houses as does improper home lighting. I see nothing that says, that proper home lighting doesn't help, but I also rarely see such lighting. It's amazing how many times you see "security" lighting which only illuminates the law. Are they scared someone will steal the grass?
  • suckered! (Score:4, Informative)

    by Quadraginta (902985) on Wednesday February 13, 2008 @04:53PM (#22411114)
    Blacklight Power is a well-known combination of perpetual-motion and pyramid scams.
  • Re:Color Issues?? (Score:4, Informative)

    by Overzeetop (214511) on Wednesday February 13, 2008 @04:53PM (#22411128) Journal
    There are no good white basketball players...

    Oh, sorry, I had a top secret flashback for a moment. White LEDs, iirc, are essentially fluorescent light sources which use the LED to stimulate emission in several bands based on the phosphors used. As such, they are still discrete (though not monochromatic) frequency lights and cannot creat and exact replica of incandescent (i.e. blackbody) radiation. I've not seen much on LED CRIs or color temps...most people are just so amazed that they produce "white" light that they don't seem to care. White LEDs, as a result of how they work, are only about 1/2 as efficient per watt as their more efficient monochromatic counterparts.
  • by ajlitt (19055) on Wednesday February 13, 2008 @05:13PM (#22411412)
    Home Depot and Ikea offer free fluorescent (tube and CFL) recycling. Of course, you still have to handle the bulbs properly during use and recycling, and I'm assuming that recyclers can recover a large portion of the mercury.
  • Re:Color Issues?? (Score:4, Informative)

    by MasterC (70492) <cmlburnett@gm[ ].com ['ail' in gap]> on Wednesday February 13, 2008 @05:41PM (#22411780) Homepage

    As such, they are still discrete frequency lights and cannot creat and exact replica of incandescent (i.e. blackbody) radiation.
    However, that is irrelevant due to the biology of our eyes. IOW, it doesn't matter if you see light of a violet frequency or, instead, a combination of red and blue (aka purple). Really, the LED needs to just mimic the spectral sensitivity [wikipedia.org] (570nm, 540nm, & 430nm) of our cone cells [wikipedia.org]. This means we don't need actual white light (frequencies ranging from red to violet) to have white light insofar as our eyes care.

    And, no, LEDs are not fluorescent. Fluorescent bulbs stimulate mercury to emit UV light. The UV light hits the phosphorus which makes it fluoresce and produce visible light. LEDs work by jumping electrons across a band gap and a photon is emitted when it jumps back down. The high efficiency comes into play because it doesn't take much more energy than that of the band gap to make an electron jump.
  • by sd.fhasldff (833645) on Wednesday February 13, 2008 @06:19PM (#22412254)

    And, no, LEDs are not fluorescent. Fluorescent bulbs stimulate mercury to emit UV light. The UV light hits the phosphorus which makes it fluoresce and produce visible light. LEDs work by jumping electrons across a band gap and a photon is emitted when it jumps back down. The high efficiency comes into play because it doesn't take much more energy than that of the band gap to make an electron jump.

    *White* LEDs don't work that way. You might assume that white LEDs are simply three (or more) normal LEDs combined in a single package. While it is possible to make white LEDs this way, it's not the method usually used (for several reasons, including "color integrity").

    Instead, white LEDs are typically made by coating a BLUE indium-gallium-nitride (InGaN) LED with phosphorous. This is not all that different from a fluorescent bulb, which is what the GP postulated.

    Different color temperatures can be achieved by varying the phosphorous coverage. Lower coverage lets more blue through (cooler temperature), whereas higher coverage causes more blue to be absorbed and thus more of the phosphorous emission spectrum to be emitted. The dominant line in the most commonly used phosphorous for LEDs is around 580nm (yellow).

    It's also possible to get white LEDs that are made by coating a near ultra-violet LED with phosphorous (thus getting even closer to the fluorescent bulb of the GP).

    This might change in the future, with serious work being conducted in the field to improve on reliability, efficiency and color characteristics. To the best of my knowledge, however, none of the new methods (go search for yourself) are commercially available and as we all know, many things that seem promising in the lab never make it to market for any number of reasons.

    For reference, red diodes emit at ~ 630nm, blue diodes at 470nm, green at 530nm. The exact wavelength of the emitted light depends on the materials used in the LED, of course.

  • by RingDev (879105) on Wednesday February 13, 2008 @06:19PM (#22412256) Homepage Journal
    The vast majority of electric power generation in the US is coal based. So you could change every light bulb in the US and still have no effect on world oil consumption.

    -Rick
  • Re:Color Issues?? (Score:3, Informative)

    by Jherek Carnelian (831679) on Wednesday February 13, 2008 @07:34PM (#22413214)

    Hmm... if you have trichromatic light of wavelengths 570nm, 540nm, and 430nm shining on an object that absorbs everything except 550nm, then the object will appear black won't it? Whereas if true white light were shining on it, it would reflect the 550nm wavelengths and our eye would interpret that as... yellow or something. Is that wrong?
    I believe you are correct.

    There has been some work on front-projection screens to produce material that reflects only the specific wavelengths that a (matched) projector produces. The goal being to use such a screen in a bright environment where it will absorb almost all of the visible spectrum, and thus appear black, except for the specific RGB wavelengths in the projected image. Thus greatly reducing the "washout" effect of using a projector in a brightly lit room.

    I think sony has a half-assed implementation that they have been selling for a few years now - sorry that I don't have a model number, once I learned it needed more ass I didn't pay too much attention to it.
  • Color Issues. (Score:3, Informative)

    by JackHoffman (1033824) on Wednesday February 13, 2008 @11:11PM (#22415506)
    Wrong, all of it.

    The spectral composition of light sources is far from irrelevant. The only case where it doesn't matter is when you look directly at the light source (TV, computer monitor) or at a surface which reflects the spectrum of the light source evenly (e.g. a projection screen or a white wall.) In every other case, a spiky light source spectrum results in improper color perception. One red color (e.g. a flower) can modulate the spectrum in a completely different way from another red (e.g. a shirt), even though they look exactly the same under a black body radiator light (light bulb, sun) at a certain temperature. The same two reds can look as different as red and black under a light source with only a very narrow band of red light in its spectrum. The difference in the color perception can only be reduced by making the emitted spectrum as similar to that of "natural" light as possible. That's why LEDs are still primarily used in effect lighting, to shine cones of colorful light onto known surfaces.

    And yes, white LEDs are fluorescent. The yellowish stuff on the LED chip absorbs blue light and re-emits it as a broad spectrum from red to green. Because it's all so tiny, the exact amount of fluorescent spectrum light and the mixture with the original blue light from the chip is hard to control, which is why the light color of white LEDs is never the same.

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