I've long been a fan of
href="http://www.lrc.rpi.edu/programs/solidstate/SSLWhat.htm">LED
lighting, thinking that it holds a
href="http://www.technologyreview.com/read_article.aspx?id=16135&z=318&p=1&ch=nanotech">lot
of promise for reducing electricity demands. Early
on in the development of light emitting diodes, it became apparent that
they produced a lot of light and not a lot of heat per watt of energy
used. There have been two persistent problems, though. One
problem is that the light from LEDs comes out in
only one color.
The second problem is the cost.
The color problem has been solved. There are two solutions,
in fact. One is to combine red, green, and blue LEDs in a
single fixture. The second solution is to coat the LEDs with
a
href="http://mt-berlin.com/frames_cryst/descriptions/led_phosphors.htm">white-emitting
href="http://www.lrc.rpi.edu/programs/solidstate/ongoingProjects.asp">phosphor.
Having solved the color problem, the only remaining issue is cost.
href="http://news.com.com/Expert+LEDs+could+start+replacing+lightbulbs+soon/2100-1008_3-6132427.html?tag=nefd.lede">CNET
reports on significant progress.
Currently, it costs about $60 to replace a 60-watt incandescent bulb
with LEDs. They expect that the cost will be down to $20 in
two years. At that price, the payback time would be only one
year. The energy savings would start immediately, of course,
but the cost savings would take a year. But since the typical
life of the unit is 100,000 hours, the savings would accrue for a long
time.
I suspect that the first uses will be in three different settings.
Hard-to-access areas, where the longer life would be a bigger
advantage, would be a good place to start. Also, because
there is no filament in LEDs, high-vibration areas would be good
candidates for early use of the technology. The third
application would be in places where there is a lot of use of air
conditioning. The cooler operation of LEDs (compared to any
existing lighting technology) means that there you save twice.
You save once, because the lighting is more efficient to
begin with; then you save a second time, because you do not have to pay
to pump out the excess heat.
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The cost savings have to look at the payback vs. other available technologies (fluorescent), not just standard tungsten light bulbs.
I think LED with its long life compares well against them in hard to reach or always on applications -- but will come up short in many circumstances.
I realize that the media tend to compare LED lighting to incandescent, which is not the best comparison, as you point out.
One of the reasons that I am enthusiastic about the LED technology is that there seems to be a lot of room for improvement, oth in terms of efficiency, and in reducing manufacturing costs.
Another factor will be design flexibility. Although that won't help directly with the primary goal of improved energy efficiency, it could lead to some interesting designs.
One application where LEDs really shine is in flashlights. I own several LED flashlights, and I will never go back to incandescent models. LED bulbs are available in up to 5 watt models, and they provide more light for much less battery usage, compared to any other technology that I know of.
Buses and automobile rear and brake lights are already going the LED route, so are traffic lights. The other cost savings, not yet mentioned, is maintainance - the cost of getting to the failed bulb to replace it.
They are getting very bright now, way beyond what your basic AA or D cell can supply for any reasonable length of time. So the number of LEDs it takes to replace a 60W bulb, lumen for lumen, is now down to about one or two. 10W each. Big issue there is that the power supply voltages do not match. LED's are low voltage DC devices, not high voltage AC. Flashlights, car brake lights, static installations with power supply budgets, all OK for LED, but not yet the screw-in replacements for incandescant.
LED lighting is very promising. If you want to save electricity today, you should probably buy compact fluorescent lamps. LEDs will have advantages over fluorescents in that they are solid state and thus less prone to breakage, more compact, do not contain environmental hazards (fluorescent lamps contain traces of mercury), are dimmable, and allow color control.
Luxeon is one of the leading product lines, manufactured by Lumileds (which was bought by Philips last year). Many of the LED flashlights contain their product.
Osram introduces Ostar LED with output of 420 lumens
I really can't think of a more prized possession than my LED headlamp.
Another benefit of LED vs Flourescent or incandescent is the latter tends to be bright point or line lights while LED can be used as distributed light. This can be done since LEDs are so small and require so little power that they can be placed all over using thin wires.
I too have some LED flashlights, including a couple that have little generators in them, so they never need batteries.
It occurs to me that the low/heat, low-voltage operation presents safety advantages, too, when it comes to residential and commercial lighting applications.
An advantage LEDs have over fluorescents is that fluorescents often need time to warm up before they reach full brightness. LEDs don't.
LEDs may also be a better option for people who don't like the color cast of fluorescents.
I believe LED's are much better too for things that get turned on and off rather frequently. Flourescents expend a lot of energy turning on.
The use of LEDs for lighting and solid-state illumination applications is on the rise. Today, more lighting application designers are using LEDs, which offer high brightness, long life and energy efficiency, for lighting consumer, signs and signals, solid-state lighting,consumer, automotive, and industrial applications.
With this evolution from blubs to LEDs, lighting designers want to be able to find the LEDs they need for their designs in one place to help shorten their time to market issues. Avago Technologies, which provides a wide variety of LED lighting solutions to meet this need, has developed a new LED lighting portal that meets this need by providing all of its LED lighting solutions in one convenient location by five basic lighting applications. I was impressed by the way this new lighting portal was developed. Hopefully it will save LED lighting designers a lot of time in finding the LEDs they need for their appliations.
The URL for this new lighting portal is www.avagotechlighting.com.