Since this seems to be a fairly hot topic here I thought I'd give it another little shove. (And I hope Don Klipstein responds, as he seems to be one of the most knowledgeable folks here in this field.)
So it's one of the burning questions of our age: are CFLs really that much more efficient than incandescents? Should we go whole-hog over to what Homer Simpson calls the "twirly" light bulbs to save ourselves (by cutting carbon emissions, etc.)?
Plus now we have a new contender, LEDs, to throw into the mix.
If I were Ayatollah of the world, here's what I think I'd do. I would want good answers to all these questions, based on good science and not just speculation, "common sense" or other less reliable ways of arriving at a conclusion.
I would order a Grand Study of the problem. This study would not just look at the efficiencies of various bulb types in isolation: it would attempt a holistic approach, where every aspect of creating and using light bulbs is considered, not just the simple matter of CFLs using less electricity to emit the equivalent amount of light:
Seems to me there are the following aspects to consider:
Production costs: o Energy consumed by producing each type of bulb o Materials required by each type, and energy consumed by obtaining them o Environmental consequences of producing each type o Monetary cost to consumer of each type
Usage costs: o Comparative energy consumption of each type per unit of light o Comparative heat produced by each type o Longevity of each type o Comparative cost of each type, based on energy consumption and lifespan
Disposal costs: o Actual physical disposal (recycling, landfilling) costs o Environmental consequences of disposing of each type
I think these "top-level" categories should cover most of the important questions that should be answered in order to set light-bulb usage policies.
One of the most important things to consider, I think, is the fact that CFLs contain fairly complex electronics, requiring construction at the front end and disposal at the back end. How much energy does this all consume? (That little matter of mercury in CFLs also demands investigation.)
It's important to look at something like this holistically so that we don't end up embracing a policy that, to use an analogy, yields a barrel of oil while requiring two barrels of oil to produce it.
Side note on LEDs: I ran across an article someone had posted a link to in another newsgroup that's interesting, talking about how LEDs aren't ready for "prime time" as lighting devices because of a potential energy inefficiency due to the phenomenon known as "droop":
I don't care about efficiency. CFLs are MUCH cheaper in the long run. Mine have all lasted at least 6 years instead of 6 months for incandescents. Also cheaper because they provide the same brightness while using less electricity. But the number one reason I love these bulbs is that they don't throw off the ridiculous heat generated by incandescents. It's not a big deal in the winter but for those of use without AC, CFLs can lower the room temp by 5-10 degrees, at least in my experience.
If a 60 watt incandescent replacement CFL only takes 13 watts you bet your ass I'm saving money with EVERY light in the place a CFL. I don't care about production problems and I don't care about disposal problems.
Energy consumed for production and transportation: Thankfully, Osram did a study, and found that to be 2% or less of the amount of energy consumed by use during its rated life expectancy for all three types. Osram makes incandescents, CFLs and LED "light bulbs".
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For the 8 watt CFL and the 8 watt LED "bulb" studied, 98-plus% of energy consumption attributable to theior entire life cycles was energy usage to produce light, and manufacturing, transportation and disposal account for no more than 2%. What I see makes it appear that this is also true of the
40 watt incandescents studied.
With higher wattages, the percentage of energy used by the entire life cycle being electricity consumed for producing light will probably be slightly higher (more than 98%).
This study assumes 10,000 hour life for the CFL - which I consider optimistic for real-world usage. If it lasts 2/3 of that, then 97% of life cycle energy use is from electricity used to make light. If it lasts half that (which I think average actual average life of CFLs now exceeds), then 96% of life cycle energy use is from electricity consumed to produce light.
The best LED "light bulbs" on the market have luminous efficiency about the same as that of decent quality CFLs. This is supposed to be 5 times that of a 230V 40W incandescent or 4 times that of 60-100W 120V incandescents, but my experience suggests that in practice it's more like
3.33 times as good as "standard" 120V incandescents.
Longer life incandescents fare worse, with ones rated to last 3500-5000 hours usually having at most 20% of the efficiency (I think more like 24% in practice) of good CFLs and the best LED light bulbs.
CFLs and LEDs fade more over their lives than incandescents do. CFLs have slightly lower scotopic/photopic ratio than incandescents do. This is why I like to figure on a CFL producing effectively about 5/6 of its rated light output. I would do the same with LEDs despite their higher s/p ratio, since they fade over time and I have found many of their light output claims optimistic to some extent or another so far.
For a given amount of power consumption, heat production is the same.
For a given amount of rated light output, incandescents produce 4 times as much heat as good CFLs and the best LED "bulbs". But only 2.5 times more heat materializing in the fixture - a significant part of the incandescent's heat is infrared, materializing in the room but not in the fixture.
(For practical purposes, including my impressions of "real world effective useful light output", I would like to say that on average incandescents produce 3.33 times as much heat in the room and twice as much heat in the fixture as good CFLs and the best LED bulbs of same practically effective light output.)
LEDs: In a good case, 100,000 hours for colored ones, 50,000 hours for white ones to fade to 70% of original light output. Osram rates the 8 watt LED bulb in the above study to be useful for 25,000 hours. I have seen one white LED nightlight lose about half its output in 4,000 hours.
CFLs: Better ones now are rated for 10,000 hours, if not overheated and with average runtime of 3 hours per start. I still see some rated 7500 hours. My experience is averaging about 60-66% of rated life in typical home use for ones rated 6000-7500 hours.
Incandescents: The more efficient ones are either rated to last
750-1000 hours, or are halogens rated to last 2000-3000 hours. There are longer lasting ones with life expectancy anywhere from 1500 to 20,000 hours (130V traffic signal lamp used with 120V), but efficiency decreases as life expectancy increases.
Using 11 cents per KWH:
60 watt "standard" 870 lumen incandescent lasting 1000 hours and costing
85 cents: $7.45 per 1,000 hours
75 watt 1100 hour 800 lumen 3-for-$1 dollar store incandescent: $8.55 per 1,000 hours
75 watt 750 hour 1190 lumen 85-cent one dimmed to 800 lumens (65 watts, roughly 3000 hour life expectancy): $7.43 per 1,000 hours
75 watt 750 hour 1190 lumen 85-cent one dimmed to 870 lumens (67 watts, roughly 2200 hour life expectancy): $7.75 per 1,000 hours
13 watt CFL, costing $4.50, if it lasts 4500 hours, 800 lumens on a good day: $5.93 per 1,000 hours
18 watt CFL, costing $4.50, if it lasts 4500 hours, 1100-1200 lumens on a good day and usually exceeding 900 for practical purposes: $6.48 per 1,000 hours
The savings of replacing incandescents with CFLs increases as wattage of the incandescent being replaced increases.
I am unaware of any screw-in LED light bulbs that produce 800-900 lumens.
I am aware of an LED ceiling fixture that produces good or at least fairly good color incandescentlike warm white light, rated to produce 650 lumens from 11 watts and to usefully last 50,000 hours (Cree Lighting LR-6). That 650 lumens is about that achieved by 60 watt reflector bulbs and 13-15 watt CFLs with reflectors in recessed ceiling fixtures.
I somewhat remember that it is likely to be improved in efficiency in the near future - maybe to about 800-900 lumens with 11 or 12 watt power consumption.
I do not know how much these cost and they require installation.
I somewhat remember landfilling costing Philaelphia around $70/ton around 1990 or earlier in the 1990's - could be more like $100/ton now. Plus maybe a few dollars per ton to transport trash to the landfill.
If you take your dead CFLs with you to Home Depot next time you go there, proper recycling does not cost you anything. I hope the actual cost is included in the price Home Depot charges for their CFLs.
The main concern is that landfilled CFLs would release about 3.5-4 milligrams of mercury. On average, ones replacing 60 watt or higher incandescents in the USA save the environment from at least that much by reducing coal burning.
I think I answered most of the questions here, though not all. If I see a followup asking for more, I will try to get to it later this week.
Keep in mind that in this (hypothetical) "Grand Study" it's the total costs to *everybody* that count, not just what it costs *me* as a consumer. I know I can recycle my CFLs at a number of places (Home Depot, Ikea, etc.) for free; what I'm after here is the actual cost of transporting, storing, dismembering, sorting, and ultimately disposing of the remains: recycling what can be recycled and landfilling the rest. Including any energy expended in doing so.
I doubt if you or anyone else here has a figure for that, but it's a real cost, one I think would be helpful to know. (I would be interested in your educated guess.)
The Osram study on energy consumption includes "end of life" - I would think that would include disposal.
As for my cost figures - that was only direct consumer cost, though I suspect and hope that Home Depot includes cost of their recycling of brought-in dead CFLs in the cost of their new ones. If you accumulate your dead ones until the next time you had to go to Home Depot anyway, there should be extremely negligible cost and energy consumption of your transportation.
If you have AC, you pay twice for any waste heat from any light you use, once to make it, and once to force it out of the house. I'm not sure, but I think it costs more to remove the heat from the house than it does to make it in the first place.
By far most of the output of an incandescent bulb is heat, but aiu things, even the light, from both cfls and incandescent, turns to heat when it hits soomething and doesn't bounce off. Now white bounces a lot more light off of it than does black, but if bounced off all the light, you could turn off the electric lights in an all white room and it would remain lit forever. Instead it gets dark in a tiny fraction of a second. Where did all the light energy go? It turned into heat, afaik.
Not to belabor this point too much, but Home Despot doesn't actually recycle CFLs. I'm guessing that they actually sell the carcasses to someone who disassembles them and scavenges the usable material. So my question still remains: how much energy is required for this operation?
I'm also curious what usable stuff they're able to extract from all those bulbs. I can't imagine that anyone wants to reuse any of the transistors, capacitors, etc., so they must get ground up and somehow turned into feedstock for ... something.
On Aug 25, 7:52=A0pm, David Nebenzahl wrote: . Holistically yes. Include what happens to the wasted (or unecessary) electricity from non CFLs use. Here (Aug 25th) the temperature tonight is around 5 to 7 degrees Celsius (40 to 46 deg F); with a light frost warning for low lying areas! No wind. We have electric heating 95% produced by hydro power. However it has not been necessary to turn it on. The wasted heat from several incandescents, boiling the kettle a few times, operating the microwave briefly a couple of times and heat from a TV and a PC have been sufficient to keep the house sufficiently warm. So while a case can/should be made for the reduction in electricity consumption that does not have to be generated (especially by burning coal or other fossil fuel) and potential reduction in capital investment by electricity producers and distribution utilities electricity is not NECESSARILY conserved by mandating the use of non incandescent bulbs.
Thank you. That will be added as a criterion for the Grand Study. (Seriously: the amount by which indandescent lighting reduces the need for space heating.)
The unfettered marketplace will control the energy required to produce a CFL. The only common thing I can think of that costs more in energy to produce than it yields in value is Ethanol. Ethanol is a product of a government-fettered marketplace.
As far as Mercury in bulbs, remember, we've been disposing of florescent bulbs for a century without a peep of concern. But raising the issue and finding a solution to an unimportant concern does make a significant number of people feel better, so that's something.
Inacandesant by the high percantage of infrared they omit heat more, its not light you see. I have read 93-96% of energy consumed by an incandesant is output as heat, the majority of energy out put is infrared that heats. Flourescent by they way they operate are better. Incandesants to me, are electric heaters that output 4-6% light. In winter they are not as bad, but electricity costs me 50% or so more per BTU than Ng. The only place I use incandesants is my frige, can lights, and a few other things. I burn out a HD cfl and I get a new one free.
Don't get me wrong; I'd be a benevolent Ayatollah, and wouldn't necessarily depend on government mandate to dictate what kinds of light bulbs folks buy. But I'd want to know into which basket we should put all our eggs. Figure out the odds so we don't bet on the wrong horse. [Insert clever metaphor here]
Knowledge is power. If you KNOW which is the better bulb, there is the temptation to mandate its use (witness that exact fact). People should gather their eggs in whichever basket they choose, put them in their pockets, or wrap them in a handkerchief and carry them over their shoulder.
If *I* were the king of the world, I'd shoot anybody who says "we need to study this."
I've not come across any yet and would similarly replace with an LED if one blew but there is a clever little man (oops, person) inside most fridges and freezers that switches them off as you close the door. I suspect that the overall impact is minute compared to actually opening the door and keeping it unduly open!
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