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Integrated Reflector Could Lead to Ubiquitous LEDs
Andreas writes "Professor Schubert says he has found a way to raise the efficiency of LEDs to 99%. From an article on Advanced Technology: "Until now, all lighting systems, especially incandescent bulbs, generated more heat than light. But our 99-percent efficient reflectors for LEDs makes them the first candidate for light-bulb replacement that generates more light than heat," said Schubert."
"LED technology has the advantage of longer life than fluorescent. With the increase in efficiency from reflectors, they could cut power costs below fluorescent and become the TCO winners."
Also something to keep in mind is that LEDs are far more robust than fluorescent and incandescent lights. Incandescent lights can't take shocks very well, and the huge temperature delta between an on/off state reduces its lifespan significantly. Fluorescent lights are also relative fragile (ever tried replacing fifty or so of those tubes without shattering at least one of them?), and the ballast used to generate the required high voltage (most types of ballast) create quite a lot of EMI, which is bad for sensitive equipment and cables like Cat-5 etc.
LEDs generate very little heat, require only a very small current (tens of mA!) at equally low voltages, produce no EMI, are unaffected by all but the most severe shocks and last virtually forever (100,000 hours for red, green, etc. with ease).
If LEDs are made brighter, even if this makes them more expensive than other technologies, there are always some (less friendly) places where they would work very well and would be cheaper in the long term.
Site & blog: http://www.mayaposch.com
These lights use a Fresnel Lens to direct the light from the bulb or LED cluster to only the lane for which it is intended.
wikipedia link
Unfortunately DC power doesn't transmit over any kind of distance very well. AC is much more efficient for that. (Esp. at high voltages... 20,000V+)
Also, all flourecent lights have transformers in them, so suddenly it's not too unreasonable for each light fixture to have its own little transformer in it!
=Smidge=
> Unfortunately DC power doesn't transmit over any kind of distance very well.
Looking at just the wire itself, transmission losses aren't worse for DC. There are a few HVDC transmission lines in operation now. Some are used for 50/60Hz conversion.
The reason AC is used because it's easier/cheaper to efficiently step up (and down) the voltage to useful levels, as per your power transmission example.