Regular bulbs (almost) as good as CFLs

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"Chunlei Guo, associate professor of optics at the University of Rochester, ... have been able to squeeze out fluorescent-like energy performance from an incandescent light bulb. The breakthrough boils down to a laser treatment of the bulb's tungsten filament, a processing step which could one day become a standard in the light bulb industry."
Too late. Incandescent bulbs will soon be illegal.
http://www.dailytech.com/article.aspx?newsid 289
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From that article: "The pulse lasts a mere femtosecond, and delivers as much power as the entire grid of North America into a needle point size spot."
Huh? I think they left out one of the units or something, and if they didn't I don't see how using that much energy to modify the filaments could save energy on a production scale.
R
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On 6/2/2009 2:32 PM RicodJour spake thus:

Read the comments below the article: lots of sloppy "science" in the text.
I forwarded this article to my pointy-headed scientist friend. Curious to see what he has to say about this.
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David Nebenzahl wrote:

If I was interpreting the article correctly, I believe that what they were saying was that they were putting a massive amount of energy into the filament over a very short timescale. so quite possibly the total kWh used to "modify" a filament may be very reasonable, but the current drawn for that brief instant would be quite massive. nothing that couldn't be handled with a hugeass bank of capacitors.
Now whether, overall, it's worth it... or if it really works... remains to be seen. An interesting read, if nothing else. I'd certainly be inclined to buy a hotrodded incandescent bulb over a CFL given similar energy consumption (including the energy used in production)
nate
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The real problem here is that they didn't do anywhere what the headline claimed. According to the facts in the article, they can produce an incandescent bulb that produces the light of a 100W one while using only 60W. While a major improvement, that's still almost 3X the 23W of a CFL. MAybe they think they can get there with further refinement, but it isn't so yet.
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snipped-for-privacy@optonline.net wrote:

True, but there are applications where an incandescent is more appropriate than a CFL (hallway lights, outdoor lighting, etc.) so improvements in incandescent technology combined with the use of CFLs where appropriate can only reduce our overall energy use.
Plus, an incandescent can be dimmed out of the box; only a few expensive CFLs can. More savings - why use more light than you need? Use bright bulbs in all your fixtures but dim them down to a comfortable level. Bulbs will last darn near forever, and you can adjust the light level from needing a little to make up for an overcast day to much brighter on a dark night.
I for one welcome our new energy-saving incandescent overlords :P
nate
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Wasting 'light' or energy? I wonder if most people realize that the older dimmer switches used a resistor and the potentially-saved energy is just dissipated as heat - they don't save energy. The newer ones chop up the sine wave and do save energy, so if someone is trying to be energy efficient they will need to upgrade those old dimmers along with the bulbs.
R
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They do actually save some energy, because power is V^2/R, so for constant voltage, if you increase the total circuit resistance, you decrease the power. But as you point out, of the total power reduction of the light bulb, some is wasted as heat in the dimmer.
Cheers, Wayne
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There aren't many resistance based dimmers around that need to be replaced. The triac semiconductor type have been the only thing you find for the common switch replacement applications for at least several decade.
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RicodJour wrote:

Dimmers based on resistors are nowadays only slightly more common than hairy eggs.
The real energy efficiency problem with dimming incandescents is that they produce light less efficiently when dimmed. Typically, an incandescent consuming half its rated wattage produces about 20% of full light output.
If you are usually dimming them, you will probably save by using fewer bulbs or lower wattage ones - especially fewer, as long as the illumination pattern is satisfactory. (Higher wattage incandescents tend to be slightly to somewhat more efficient than lower wattage ones.)
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Jun 3, 5:53pm, snipped-for-privacy@manx.misty.com (Don Klipstein) wrote:

C'mon over to my neck of the woods and I'll serve you up some hairy eggs, then. There are plenty of older houses around here with old wiring, old fixtures, and old dimmers. I run into old knob and tube stuff on occasion. When I tell the owner how old the wiring is, they tend to freak out a bit.
R
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I work on lots of houses that still have (and are still using) knob & tube wiring. But invariably if there's a dimmer switch, it's the "modren" triac type, not some kind of ancient rheostat.
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This is interesting - there seems to be some confusion. Maybe you can help me.
I wrote: "so if someone is trying to be energy efficient they will need to upgrade those old dimmers along with the bulbs." How is it that people are reading that and construing it to mean that I said all dimmers were the older type and needed to be replaced? Right. I didn't.
Your experiences differ from mine on working on old houses. This does not surprise me.
R
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On 6/4/2009 6:13 AM RicodJour spake thus:

Well, you wrote, and I quote:
There are plenty of older houses around here with old wiring, old fixtures, and old dimmers.
As you noted, our experiences differ: I've *never* seen an old (i.e., non-triac) dimmer in a house with old wiring and old fixtures. And I've worked on plenty such houses (in the SF Bay Area). Maybe it's a geographical difference.
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As most things in construction - probably.
Unfortunately the trend around here now is for people to buy a nice older home, knock it down and put up an over-sized McMansion. Some a- holes knocked down a house from 1693. That's not a typo. Another one had two houses and a beautiful storybook cottage on the property and the owner refused to let it become a historic landmark (even though one house was from the late 1700's) as they had "plans" for it and didn't want their hands tied. Their plans went up in smoke with the bankruptcy, the judge (who I swear someone got to) sold it for a pittance to a lawyer (who is now in jail) and the lawyer promptly knocked down all three houses and took down about two hundred trees. The only think the building department could get him on was for "unlicensed demolition". He started building a monstrosity before he got put in the pokey, it languished uncompleted for years, and just was completed a couple of years ago.
R
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A femtosecond is 10 raised to the -15 power. So, while it's a lot of power, it lasts for such a short time, that it's not much energy at all. If it was any significant amount of energy, it would vaporize the entire filament, not just change it.
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On Jun 2, 7:11pm, snipped-for-privacy@optonline.net wrote:

I know what a femtosecond is, even though I've never actually measured one (I have a cheap watch). The article said that for that femtosecond the power output to convert the filament was as much power as the entire NA power grid puts out (assumedly for the same femtosecond). Multiply that femtosecond power requirement by how many bulbs produced in {insert time period here} and a lot of those decimal point zeros fall off and the energy spent to save energy might be quite large indeed.
It's a crappy article written about something very interesting.
R
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Even if you multiply somthing that is 15 zeros small by a hundred or a thousand, it still isn;t going to be a number that amounts to any extraordinary amount of energy.
Let's say you make 1000 bulbs a second, which would be a hell of a nice production rate. The total generating capacity of NA, which is certainly more than the actual grid usage, is about 1 tera watt. Now let's figure out how much energy in KWH it actually takes to hit each one of those 1000 bulbs with that laser pulse:
1.0 E12 total NA capacity in watts
Convert to Kwatts:
1.0 E9 KW
Which would be 1.0 E9 KWHours if the pulse lasted an hour, but it only lasts a femtosecond, divide that by 3600 to get to seconds
2.8 E5 KWH
then by 10 E15 to get to a femtosecond:
2.8 E-10
then multiply by 1000 bulbs:
2.8 E-7 KWH is the energy it actually takes to hit those 1000 bulbs made in one second.
In an hour it would use:
1.0 E-3 which is 1 thousandth of a KWH of energy, or 1 watt hour. Clearly an amount insignificant even compared to household usage.
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entire grid of North America into a needle point size spot."
Huh? I think they left out one of the units or something, and if they didn't I don't see how using that much energy to modify the filaments could save energy on a production scale.<<
It's not all that much "energy" but a small amount of energy put forth in very (very) short time.
Note that materials that tend to absorb a certain frequency/color of light also tend to more efficiently radiate that frequency/color more "efficiently" when heated. I guess the idea is that the bulb can radiate the same amount of light at a lower temperature.
That would reduce heat loss by convection (there is some gas in the bulb) and conduction via the leads. But a lower temperature might lower the "color temperature." Of hand, I can't see whether the reduction in color temperature will help efficiency. I know that incadescent "photo flood" lamps are consided to be efficient but they pay for that efficiency with short life.
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Yep, so it would seem. Trader did the math which I was too lazy to do, but there was something about that article that bothered me. It was poorly written and maybe I'm hung up on that, but I don't know, it seemed to me to read like one of those studies funded by RJ Reynolds that found you could smoke like a chimney and it wouldn't cause cancer. You know, bullshit.
The number crunching Trader did was based on some assumptions that were off a bit. How many light bulbs do you think you have in your house? I'm sure I have well over a hundred. There are 13 in the room I'm in. There must be many billions of bulbs in the US. Frankly I wasn't interested enough to do the math, but there are still questions due to the lame ass writing in that article. "As much power as the entire NA grid"...does that include nuke, coal, wind, the whole shebang? Trader used 1 terawatt and said that was certainly more than the NA grid. I'm not sure what the NA number is, but the worldwide consumption estimate was 15 terawatts in 2006, with the US consuming 25%.
Anyway, I'm all for efficiency as long as it is real efficiency and doesn't come with serious "side effects". The mercury in CFLs being one of them.
R
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