replacing CFLs with LEDs

Most of the wire loss between the meter and the outlets or in-wall heating units is either outside or partially outside my insulated building envelope. The breaker panel is at the far corner of the garage. The garage portions of the wire runs are completely outside, the attic runs are mostly outside, and crawl space and exterior wall runs are half way outside. Only the interior wall runs are completely inside, but those account for very little of my (now backup) electric heat wiring.

If we don't count hot exhaust air dumped out a chimney as usable heat, we shouldn't count this exterior and partial-exterior wire loss either.

 

Well, this type of heater (quartz tubes inside a wooden cabinet) has been peddled for over 20 years as I recall, and initially the selling-point to justify the $800 price, was that these were "much more efficient" than other electric heaters. My point is that virtually 100% of the electricity consumed by any electric heater results in heating the room. The same can be said for most forms of lighting as well.

Line-loss in the distribution system is not often a subject of debate, but it's safe to say that nearly all of it escapes as heat. There was even once a proposal as I recall to temporarily overload the wires to melt off accumulated ice. Even the electromagnetic radiation that escapes is eventually absorbed somewhere and dissipated as heat.

That's why power transmission systems utilize higher voltages, which are more efficient over longer distances. I have even read about a superconducting powerline somewhere, but I don't recall the details.

 

The last super conducting transmission line I remember reading about was proposed for underground in NYC. I do not know if it was built.

Bob Wilson

 

It appears that the Germans turned on a superconducting transmission line last year. 1 kilometer long, 40 MW.

 

World premiere in Essen: RWE integrates superconductor cable for the first time into existing power grid - Nexans
1KM is built as kind of a proof of concept.

We made superconductors in chemistry class, but needed liquid nitrogen to make them work (actually half the lab did something wrong and they didn't superconduct. The other problem was that they were brittle so it is hard to make them long. Some technical challenges have already happened, but more are needed if long lines are going to superconduct in warm weather. Progress is definitely being made though.

Most of the grid only loses 6% of power. To decide that it is worth it replacing a line needs to cost less than this loss is worth.

 

Just in time for FCVs.

Bob Wilson

 

These superconductor lines can transmit high amps at residential level voltages with minimal losses. The immediate advantage would seem to be savings in expensive and bulky transformers, but perhaps they will revolutionize trains. They might also be needed in a distributed, 'smart' power network.

 

Fillup: (a) gas tank, (b) battery, and (c) liquid Nitrogen (LN2) for superconducting wiring...to the 1 Gigga-Watt SOUND SYSTEM (ha,ha)!

 

From what I knew from decades back the technical issues with supercondactor were:
1) need for low temps
2) very limited current.

When current went over threshold it would revert to being normal conductor. We are talking miliamps here. Alot of R&D, special metallurgy went into resolving these.

Don't know where they are at, but it is most likely high voltage/low amp vs low voltage/high amp application.

 

Not a lot to add, many of you folks obviously have spent a lot more time researching and experimenting than I have.

I've always liked the idea of LED, but cost was just not feasible. Lately I've been seeing more and more of them show up at my favorite local discount returns and overstock warehouse, and have been scooping them up as I find them. Generally paying $1-3 for bulbs, $5 for exterior flood lights, $5 for exterior low voltage landscaping lights, and $5-10 for can replacements. Don't usually have a lot of choice of brands or color temp, but very happy with the results and price so far. Slowly working through the house from most to least used lamps, probably about 1/2 done so far though I have a new batch to work through that will get me closer to 70-80% probably. I save the working CFLs I take out and reuse them in other locations when I have burn outs, though they are starting to pile up a bit.

I'd really like to switch out the 4' Fluorescent tubes in my workshop / garage, but those still seem pretty pricey. Picked up two Philips 4' LED tubes (non-working) for $1 each at the warehouse though, so those will be fun to take apart and play with Looks like they had mechanical damage (bent/creased) so there may be a chance to repairing the traces running down the tube...

Rob

 

@miscrms

I am CFL myself, not planning to go LED any time soon. LED may be more efficient but the small difference comes at high cost. Here is info from Wikipedia:

Minimum light output (lumens) Incandescent Compact fluorescent LED
450 40 9–11 6–8
800 60 13–15 9–12
1,100 75 18–20 13–16
1,600 100 24–28 18–22
2,400 150 30–52 30[37]
3,100 200 49–75 Not available
4,000 300 75–100 Not available



As you see small efficiency increase does not translate into practicality. If I have 10 100w equiv burning 10 hours a day, I am saving only 0.6kWt/hr a month.

LEDs are viable option if there is no CFL equivalent, but they are not cost effective most of the time. Wait until prices drop to 2-3$

 

At this point, there's not a great lot of difference between fluorescent and LED efficiency, at least I haven't seen it yet. Certainly the upgrade cost is a major factor. I'd probably switch just to get the better technology, and they haven't yet figured out how to engineer a shorter lifespan into LEDs.

My outdoor motion-floodlights were CFLs, which worked fine, but I wasn't crazy about the 1-second delay they needed to turn on. Also, in colder weather, they were quite dim until they warmed up a few minutes later. I switched to LED floods a few years ago, and they have none of those drawbacks.

 

keep looking - there are retro-fit can LED's that have similar brightness ouput (appx 700 lumens) to CFL's ... and for those of us who like dimming functions - CFL's just don't have the low range that LED's have. Then, the important things;
1- wattage. LED's of that brightness can run on as little as 9 watts (on high level brightness) where as CFL's - you're typically looking at 15 watts.
2- life expectancy LED's - years longer.
Prices have come down on LED's too. I just saw retrofit can lights at costco for (w/ utility company instant rebate) under $10.
.

 

Not so much. The LED lasts, but the heat fries the other electronic elements much faster.

 

Brightness is easy, luminous efficacy is not.

 

Also, thin surfacemount light fixtures that look very similar to those retrofit can lights are available, only in LED. We like that clean flush look much better than our original ugly pendant fixtures. While I haven't yet seen these at Costco, they have reached hardware stores, and some have utility instant rebates.

LEDs also work well in outdoor and unheated locations in cold climates, where most CFLs can't take the winter cold, and the few that can still need significant warmup time.

Even the LED die will suffer from the heat, if thermal design is inadequate or defeated by improper installation or application. Unfortunately, that may be a lot of them.

 

The early white LEDs "first-gen" were never very bright. I suppose there was a generation before that, but it wasn't commercialized to my knowledge. White phosphors existed for a long time, and LEDs that were made this way weren't very bright or efficient.

The invention of the blue LED is what's said to have made the white LED possible. It had existed for decades before that, but because of its dimness, had very narrow application in something like the hi-beam indicator of a VW Rabbit. Shuji Nakamura of the Nichia Corporation helped develop the first bright one, and for that he won the Nobel Peace Prize, although his employer reaped all the financial benefits, and he got only a small stipend of about $10,000. For that reason, he renounced his Japanese citizenship and moved to Silicon Valley.

White LEDs only recently became as efficient as fluorescent lamps, and some have even exceeded metal halide lamps. The addition of yellow dots on the emitter has shifted the visible spectrum to appear to us as pure-white, even though it's not the same composition as sunlight. The theoretical maximum of efficiency is said to be 2 or 3 times higher than it is now, but it's probably not worthwhile waiting for something that may never be achieved in our lifetimes.