LEDS Save energy

I was coming up in the elevator from getting lunch today and the news display screen said that LED lighting is expected to save 10% of world-wide energy usage by 2025.

I found a link on the Web that was exceprted from a Feb 11th NY Times article

"Light bulbs, which lighting experts deride as heaters that happen to give off visible light, work by forcing electricity through a metal filament in a vacuum. About 6 percent of the energy ends up as light. Today's light chips are up to five times as efficient…One widely cited study for the Energy Department concluded that the widespread use of solid-state lighting by 2025 could cut electricity demand 10 percent and save consumers $100 billion. "

Anyway, I thought that interesting, but a long way out.

Cheers,

Richard

Interesting, but not exactly in line with what I've read elsewhere. Other sites, and I would have to grub for them since I was surfin' without savin', list current LEDs as somewhat more efficient than regular light bulbs but about the same efficiency as halogen lights. Lumen output listed by some flashlight manufacturers who sell both LED and incandescent lights generally supports this. I think the real LED advantage, long term, will be more along these lines:

-- Long life applications, such as traffic lights, benefit from LED use right away - but that's only because incandescent traffic lights run way cool/red to extend their life since replacement is such a pain.

-- Current LED benefit for more conventional light use is that they are shockproof, don't burn out, and hold their color as they are dimmed. Energy savings isn't a major driver.

-- The future will probably see more efficient LEDs. Maybe that's an underlying assumption of the article. If so, I would take it with the proverbial salt grain. When they're here, great. Until then I'm happy with the non-energy advantages.

more on why it works so well in traffic lights is that in order to have enough brightness through the color filter those bulbs typically run at 200 or even 250 watts. So even if LED's aren't more efficient, they produce the proper color so much less overall energy is wasted. No filters necessary.

A normal lightbulb passes current thru a piece of Tungsten (Wolfram) which causes the metal to get hot and "make light", as we know - most of the energy is wasted in heat

A LED is a far more eff. means to make light than to just make heat and get light as a by-product

I have talked to the engineer that worked on replacing the light bulbs with LEDs for the city of Portland

The normal light is a 66w long lasting special bulb which the crews replace every 6 months, they have replaced these incandescent lights with 12w LED versions, but still use the existing filters/bases - since the replacements are "drop-in"

I think that in the future as more LEDs become accepted as lighting solutions and traffic lights that the new ones will just use the color and they will use a clear-filter instead

Yes, replacement is a "pain", when you factor in the number of people needed for the job, the rental time on the bucket-truck and the traffic mess; the LED is more expensive at first, but will save a city a LOT of money

I have only seen RED and GREEN, no YELLOW as of yet

Yeah, I've seen only the green and red traffic lights replaced by LEDs (the original filters are removed here), and the pedestrian lights too. I don't know if the yellow is still an incandescent, but all I see is one source of light from it, so I think it's still a bulb (could it be a luxeon star?).

I like them though. They look better, and they are actually brighter! At night on streets with less abient light, they light up the dark areas, just a little bit, but the older incandecents did not even make noticable reflections. The only drawback is that residents will have to put up with brighter flashing lights at night.

INRETECH said:
The normal light is a 66w long lasting special bulb which the crews replace every 6 months, they have replaced these incandescent lights with 12w LED versions, but still use the existing filters/bases - since the replacements are "drop-in"

That would explain why I've seen unmistakeably LED color behind old-style filters. It would also account for why I've not yet spotted any of the 95% green 5% blue ones you mentioned some time back.

I have only seen RED and GREEN, no YELLOW as of yet

Nor have I in Oregon, but I've seen some here in Minneapolis/Edina. They are recognizable by their sodium-yellow color (little red in them as compared to incandescent amber) and strobing effect when the eye is moving past them.

[ QUOTE ]
Catapult said:
The only drawback is that residents will have to put up with brighter flashing lights at night.

[/ QUOTE ]

[ QUOTE ]
Canuke said:
They are recognizable by their ... strobing effect when the eye is moving past them.

[/ QUOTE ]

Sounds like they are already dimmed by pulsing, they could probably just dim them some more if the brightness became a problem.

If I'm not talking out of my Arse here, I believe I have seen Yellow LED flashing lights down hwy 35 near Alvin. The reason I think that is what I have seen is when the southbound flashes on it blinks once quite fast then stays on a few seconds. And I believe that I saw multiple LEDS.

Stay tuned, I'll be going that way again pretty soon!

As an aside, the City of Pasadena has some red lights with a zenon strobe in them that flashes like a cop cars lights when the light is red. Four of then are at the corner of Red Bluff and Genoa Red Bluff.

I didn't mean that the traffic lights were really pulsing. I actually meant the flashing hand formerly know as don't walk, turning to walk, then back, the green turning to yellow to red, and over again. If you stand around them long enough at night, it can get a bit annoying.

I have not noticed any pulsing from these LEDs.

Oh ok. I understand. It does sound annoying. Makes me glad I live in a small town.

Another LED Replacement item are RailRoad traffic signals. Namely the big red lights. We have a couple here. I had to stare at it a bit to make sure it just wasnt the lens tricking me. As the light flashed I could see the individual LED's slowly fading, some faded quicker than others and that told me it was LED.

They just didnt blink ON then OFF. I think that would unnerve people not used to LED's being able to change that quick.

They have replaced all the traffic lights in Orleans parish and some in Jefferson with Green, Yellow, and Red LEDs. The yellow almost looks kind of orange, and the green just about blinds you at night when it changes from red.

I was sorta correct about something. I still don't know about the flashing lights down by Alvin.

But there are green, yellow and red LED traffic lights all over the place around Houston. Not so much Houston proper (as Mayor Brown has this town in a hell of a financial mess!) but Pasadena and the Counties seem to have embraced LEDs.

Only one problem. And I'm probably looking at it with too much logic. If you shut down an intersection to change say the Red signal to LED, WHY THE HELL don't you change all three? Yep, that would make TOO much sense.

I'm living in "satellite-city" right after the Moscow border, and local administration replaced all old traffic lights two years ago. They bought new ones (each has large plain cluster of 2/5inch LEDs with red, amber and blue-green color) from one russian semiconductor factory "Proton" situated in Orel city (http://www.proton.orel.ru/catalog/prodeng.html). And no one element in this new traffic lights was broken and replaced for this two years! Even on lights with stands damaged by accident. Their colors are still perfect, and nobody tries to steal lightbulbs. 8) In the center of Moscow there are som older (imported) traffic light (they works for 5-6 years) - they are not so good (yellow-green color instead of green, bad visible angle), but still works fine.

"-- Current LED benefit for more conventional light use is that they are shockproof, don't burn out, and hold their color as they are dimmed. Energy savings isn't a major driver."
You didn't mention that LEDs are more efficient when dimmed, while normal bulbs get less efficient when dimmed.