Beth: Incandescents have long been optimized to work on our common 110V power supplies, and therefore need no extra circuits to adapt the input source to the output. LEDs are more complicated. With an LED, you need to understand the input source and its variability. On the output side, you need to understand optical requirements and the amount of lumens you want to generate. All of this will be worked out over time, though, as more LED apps pop up.
The energy saving of the LED streetlights is impressive. We had a different issue with LED parking lot lights. Unlike the incadescent lights which were too hot for bird nests, the LED lights did not have same heat which allowed a good spot for birds to nest. With no solution from the manufacturerer, we returned the lights for credit and re-installed the old lights. This was a while ago, and I hope that this potential problem has been addressed.
Why is it nothing in the article speaks to the bottom line. Efficiency, usability and durability. Sodium lights can have efficiency of 200 lumens/watt. LEDs have 100. See wikipedia.
LEDs have wideband, selectable wavelength. Sodium is narrow, harsh and often color-blinding.
Newest LEDs and arrays have unproven durability and must be housed properly to account for icing conditions.
Not showstoppers but definitely considerations. A recent energy survey of my mom's residence resulted in all incandescent bulbs replaced with slow, low-lumen CFLs 18 months ago. I have since reverted half of them back to hot, quick-on, high watt and useable halogens. Solar arrays on the roof keep her feeling green. Not one size fits all for LEDs either. LEDs work great for landscape and atmosphere lighting. For handiwork and reading, give me a big bright soft-white every night or day.
As engineers and designers, we need to stop chasing fads and letting marketers yank us around. Just the facts, ma'am, just the facts.
Beyond the cost barrier, what have the downsides been for a broader array of LED applications? I've run into plenty of downsides with CFL lights, which frankly aren't compelling enough to justify the added expense and the potential energy savings.
LED Street Lights have gained ground and are being implemented right here in Stamford and Greenwich CT. LED lighting is certainly the wave of the future. However, only by educating the public to the true savings of LED bulbs will they become commonplace. The initial cost can sometimes seem high. It is only after comparing the cost vs savings over time do you see the real benefit of LED lighting solutions. I commend all cities and towns that are reducing costly energy consumption by utilizing energy efficient solutions.
Beth, the laptop I am using now had LEDs for backlighting for the disply. It helps the battery last much longer. LEDs in this application replace EEFL lights, which are fairly effecient compared to incandescent.
As the price comes down they will replace other types of bulbs. Just the much longer lifetime helps. Even at home, not having to replace bulbs is a plus. For something like streetlamps bulb replacement is a very costly thing. This is a good trend.
Incandescent replacements have some fantastic advantages. I recently replaced the landing light in my 172 with an LED lamp. The constant vibration and heat make incandescents a poor choice for the cowl mounted landing light location in older Cessna's, but that's the only technology that was available at the time. Considering the promise of greatly improved life and a current draw that's nearly 1/10 of the original, the LED lamp was an ideal choice. Since the landing light only pulls a couple of amps and has such great life, I leave it on all the time.
The only disadvantage I've seen to incandescent replacements is the waste heat from traffic lights. Now there's not enough heat to melt the snow off here in blustery Chicago.
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