Compact Fluorescent Lights, Energy, and Mercury

We recieved several responses to Dave’s post this week on the bizarre “Save the Light Bulb” movement. A movement that seeks to ban energy efficient compact fluorescent lights (CFL) and return to the old, energy expensive, incandescent bulbs. The primary critique is that CFL’s contain mercury, and thus, any environmental benefit is negated by mercury exposure when the bulbs break or are thrown out.

A bright idea

First, a nod to the validity of the point. Yes, CFL’s do contain mercury. Older designs contain up to 4 mg of mercury, while newer, more advanced bulbs contain 1.4 – 2.5 mg of mercury. The mercury is essential to the CFL’s function, so it’s in the light to stay. If the bulbs break, that mercury will be released into the environment. CFL’s should not be thrown away, but disposed of properly by your local recycling agency. CFL packaging does not have detailed disposal instructions so that people know not to treat CFL’s like normal light bulbs. That is an over site that should be addressed by CFL manufacturers.

The real question is “Does the mercury in CFL’s cause more environmental harm than the energy gains from using CFL’s?” To answer that we need some numbers:

  • Amount of mercury in a CFL (we’ll use the highest figure) – 4 mg
  • Amount of mercury in an incandescent bulb – 0 mg
  • Energy consumption of an average CFL – 20 watts
  • Energy consumption of an equivalent incandescent bulb – 75 watts

You can see immediately from these numbers that incandescent bulbs don’t directly release mercury into the environment, but there is one final number that matters to this equation:

  • Amount of mercury released by a coal burning power plants (2006, most recent available data) – 50.7 tons or 0.0234 mg/kWh

So let’s take the average life of a CFL, 7500 hours. That comes out to 150,000 watts, or 150 kilowatts. At 0.0234 mg Hg per kilowatt, we get 3.51 mg of mercury. Add that to the 4 mg we’ll assume will be released when the bulb breaks, and we get 7.51 mg mercury.

Now compare to an incandescent bulb over the same time frame. At 75 watts over 7500 hours, we end up with 562,500 watts, or 562.5 kilowatts. That works out to 13.16 mg of mercury.

So, even if we buy the least advanced CFL’s and don’t dispose of them properly, they’ll still release only half as much mercury into the environment as an incandescent light.

But wait, coal-fired plants only produce half the United States energy. These equations assume 100% of the power is from coal plants. Ok, lets cut the mercury production in half to account for energy production from energy sources other than coal.

  • Mercury production by CFL’s – 5.76 mg Hg
  • Mercury production by incandescent lights – 6.81 mg Hg

So even with our most conservative estimates – 50% energy from coal, highest mercury content in a CFL, everyone throws away their bulbs – CFL’s still win out.

And, when you factor in low mercury bulbs and proper disposal, that mercury production drops to 1.76 mg Hg over the course of the bulb’s life. Couple that with the huge energy savings (those kilowatts aren’t free) and you have to wonder why anyone would be fighting to save the incandescent light bulb.

~Southern Fried Scientist

Postscript – why is it that we only bust out our calculators for the mercury posts?

    • The “dirty electricity” hoax is yet another sad case of pseudoscience hokum. Science-based medicine did a comprehensive takedown of the issue. To quote:

      The notion that EMF or dirty electricity causes a health risk, and that CFLs are a significant source of exposure, is not based upon any compelling science. Further, such claims stem mostly from a single researcher who appears to spend most of her time spreading fear about EMF than producing quality research. The media and the public should not be confused by this lone researcher on the fringe into believing that “experts disagree.”

      There are no documented negative health effects from using CFL’s. It is rather unfortunate that various fear mongering groups are impeding environmental responsibility.

  1. Lighting makes up about 2% of the ENTIRE electrical draw. I wished the environs would realize that banning bulbs would not do a damn thing toward the total amount of electricity that power gens must keep online for peak power (when it’s hot and everyone is running air conditioners). I repeat, it WILL NOT MAKE A DIFFERENCE. It’s all about HVAC/electric stoves/dryers and other true high current items.

    The CFL movement is so misguided it makes my head explode. The environs must wake up and realize that these bulbs will not be recycled. If you live in a rural area and the nearest recycle center is fifteen miles away, that bulb is going into the trash or worse yet, burned. Each bulb contains a dot of mercury about the size of the dot at the end of this sentence. Hundreds of these bulbs going into the trash can, and that dot quickly adds up.

    There is such a disconnect when comes to these bulbs. I see post after post of “They don’t last as long” or “I replaced four of these bulbs while that incandescent in that lamp has been in there for over a year” yet they still buy them?? There’s a elementary school in this area that was using these in the bathrooms of the portable classrooms. The maintenance man was replacing the bulbs for the SECOND TIME IN SIX DAYS. These were GE CFL’s with the u shaped tubes. Guess what, he was replacing them with 100 watt incans. The constant on/off cycle from the students were killing the CFL’s. They were lasting less than three days.

    These bulbs are a known fire hazard when used in circuits with dimmers or in this case, hung upside down.

    http://www.youtube.com/watch?v=B0JFH5BOZwE

    http://www.youtube.com/watch?v=Ad7vhHfjgC0

    Massachusetts banned them from being thrown away in regular trash.

    http://www.youtube.com/watch?v=a8I0OIMoqKE

    So essentially what we are doing is banning a safe, effective commodity that’s essential to modern life, with one that needs instructions for cleanup, can’t be used upside down, in enclosed fixtures because of heat, has poor color rendering, can start house fires if used improperly (and this is very easy to do), has very little bearing on real world power generation, in ceiling fans (and this on the package), can’t be used in cold climates, can’t be used on dimmers, (and the dimmer bulbs are expensive and not really effective), can’t be used on security light installations with motion detectors. In short, about 50% of the intended uses.

    GE was one of the major reasons why these bulbs were pushed so hard. Producing incandescent bulbs were no longer profitable for them and want the incandescent out of the way. Follow the money.

    • Wow, congratulations Art, your comment was a textbook case of logical fallacy, intentional deception, and just plain failing to read the article. In fact, it’s so characteristic of the drive-by fearmongering left by concern trolls and special interest groups, that I’m going to give it a complete dressing down.

      Lighting makes up about 2% of the ENTIRE electrical draw. I wished the environs would realize that banning bulbs would not do a damn thing toward the total amount of electricity that power gens must keep online for peak power (when it’s hot and everyone is running air conditioners). I repeat, it WILL NOT MAKE A DIFFERENCE. It’s all about HVAC/electric stoves/dryers and other true high current items.

      Well, even if this were true, which it isn’t, 2% is still 2%. The US consumes 29 PWh per year (that’s 29 quadrillion watts), so 2% is 580,000,000,000,000 watts. But lighting accounts for 11% of energy use in the average US home (and this is across the whole United States). You can do the math on how much mercury that will produce.

      The CFL movement is so misguided it makes my head explode. The environs must wake up and realize that these bulbs will not be recycled. If you live in a rural area and the nearest recycle center is fifteen miles away, that bulb is going into the trash or worse yet, burned. Each bulb contains a dot of mercury about the size of the dot at the end of this sentence. Hundreds of these bulbs going into the trash can, and that dot quickly adds up.

      So what? The entire point of this article was to show that even is every CFL were disposed of improperly, the mercury released would still be less than with incandescent bulbs. Thanks for reading.

      There is such a disconnect when comes to these bulbs. I see post after post of “They don’t last as long” or “I replaced four of these bulbs while that incandescent in that lamp has been in there for over a year” yet they still buy them?? There’s a elementary school in this area that was using these in the bathrooms of the portable classrooms. The maintenance man was replacing the bulbs for the SECOND TIME IN SIX DAYS. These were GE CFL’s with the u shaped tubes. Guess what, he was replacing them with 100 watt incans. The constant on/off cycle from the students were killing the CFL’s. They were lasting less than three days.

      Ah, the classic canard of all fear mongers – “I CAN HAS ANECDOTES!!!!”

      Say it with me now, anecdotes are not data. For every “the CFL burned out” story you have, I have dozens of “my CFL’s are still going strong.” I’ve been running my house for almost 5 years and not a single one of the probably 50 CFL’s have every burned out. But that’s also an anecdote. On average, CFL’s last significantly longer than incandescent bulbs. There’s just no way to argue against that.

      These bulbs are a known fire hazard when used in circuits with dimmers or in this case, hung upside down.

      http://www.youtube.com/watch?v=B0JFH5BOZwE

      http://www.youtube.com/watch?v=Ad7vhHfjgC0

      News flash, incandescents are also a fire hazard. In fact, most household electrical fires are cause by people overloading their circuits with high wattage incandescents. Yes, CFL’s occasionally start fires, but incandescents, which put out 215 – 500 degrees of heat start more fires.

      Massachusetts banned them from being thrown away in regular trash.

      Good for them, that’s what government is supposed to do. We’ve banned plastic bottles from our trash down here, does that mean plastic bottles will jump out an throttle us in our sleep? No. It’s just means they have special disposal instructions.

      So essentially what we are doing is banning a safe, effective commodity that’s essential to modern life, with one that needs instructions for cleanup, can’t be used upside down, in enclosed fixtures because of heat, has poor color rendering, can start house fires if used improperly (and this is very easy to do), has very little bearing on real world power generation, in ceiling fans (and this on the package), can’t be used in cold climates, can’t be used on dimmers, (and the dimmer bulbs are expensive and not really effective), can’t be used on security light installations with motion detectors. In short, about 50% of the intended uses.

      Nope. That’s just you making shit up.

      GE was one of the major reasons why these bulbs were pushed so hard. Producing incandescent bulbs were no longer profitable for them and want the incandescent out of the way. Follow the money.

      And finally, the ultimate is absurd fear mongering bullshit – the invocation of a vast conspiracy. Yes. They’re all out to get you. Especially those evil environmentalists that somehow control the government despite a constant uphill battle to get practical sensible environmental regulations passed because they have to deal with an army of fear mongering dunderheads.

    • “The “dirty electricity” hoax is yet another sad case of pseudoscience hokum.”

      It’s not a pseudoscience hoax: it’s fact. Your “data” is biased pseudoscience.

      “Lighting makes up about 2% of the ENTIRE electrical draw. I wished the environs would realize”

      The environs are bought out by the lighting corporations, and most of the environ websites are outlets of lighting industry propaganda.

  2. Hey if folks want to trash their CFLs and jump back on the old energy in-freaking-efficient incandescent light bulbs, send them to me! They aren’t unsafe, you just have to be careful about their disposal and based upon how much longer CFLs last, that isn’t that big of an issue. Good article man.

  3. What about mercury distribution? With the bulbs any exposure is happening in the places that you spend the vast majority of your time. With power plants it seems like the mercury is spread throughout the environment rather than directly into homes or businesses.

    • Exposure only happens when the bulbs are broken, and the mercury release is very slow, which means that most mercury leakage from CFL’s will be occurring in landfills. It’s not like breaking an old mercury thermometer and having a pile of quicksilver sliding around the floor, the mercury is coated to the inside of the glass.

      Direct exposure to mercury from breaking a CFL would be less than eating a tuna fish sandwich.

  4. For just the bulb itself your figure for mercury released into the environment by CFLs appears to be high if I’m reading the Energy Star page correctly. Energy Star says that only 11% of the mercury from a broken CFL goes into the air and water because most of the mercury vapor gets bound to the inside of the bulb. On the other hand you have not considered whether mercury enters the environment during the mining and manufacturing phases and whether it takes more or less energy to produce a CFL. I don’t see how there can be a comparison without knowing what those figures are.

    You dismissed some of what Art said a little too casually. He wasn’t just making shit up. Energy Star site says some CFLs shouldn’t be used in enclosed fixtures. The GE Lighting page says don’t use CFLs in enclosed recessed fixtures, they recommend not using CFLs in ceiling fan fixtures and dimmers need specifically designed bulbs . Don’t assume that any CFL can go in any fixture. Make sure to buy the correct bulb.

    While you may be comfortable with CFLs despite their potential for introducing a toxic substance into your house not everyone feels that way. Those people don’t want to give up being able to choose an inexpensive non-toxic bulb.

    The reason I even ended up at your blog is that I’m trying to see what kind of evidence there is for claims made about CFLs. I have a feeling that I won’t be able to substantiate very much because what I’ve found so far is mostly claims without citation. I’m looking for a little more than someone confirming or denying my own preconceived ideas.

    • Fair enough, it’s impossible to go all the way down the production chain to mining at find the contribution per light bulb for every step in the process, but while that may increase the relative contribution of each, it doesn’t change the fact that the above results provide a reasonable baseline for comparison. Find the numbers to compound the model and I’ll add them in.

      While there are safe use recommendations for CFL’s, there are also safe use instructions for incandescents, and far more house fires are caused every year by using improper wattage incandescents. I’m still trying to find the national number for tho, but don’t assume that any incandescent bulb can go into any fixture either.

      While you may be comfortable maximizing your mercury input into the environment, I’m not. Just because the mercury is being diffused over a larger area doesn’t mean it’s harmless. Perhaps people who want incandescents should store that 13 mg of mercury in their houses instead of exposing me to it?

      I’m curious about CFL claims, too. I still haven’t found any compelling evidence for why they shouldn’t be used, but plenty of anti-CFL propaganda.

  5. No, it’s not a reasonable baseline for comparison because you don’t know how much mercury is released into the environment by the production of CFLs. If you don’t know the number, you can’t just set it to zero. And since you don’t know how much mercury is actually being released into the environment by CFLs, you also don’t know if you are minimizing your contribution by using CFLs.

    Besides being based on a not yet proven hypothesis, your comment about people who want incandescent bulbs having to store mercury in their homes just isn’t conducive to the discussion.

    It’s not my intention to give you evidence not to use CFLs, but as I said, I don’t think you’ve made a case for the claim that you made. It’s not positive or negative for CFLs, just unknown. I haven’t found any numbers for CFLs and mercury mines though I did find a news report about workers in some lighting factories in China having mercury poisoning. Maybe I’ll get lucky and stumble on something.

    • You can always keep adding unknowns until there’s no way to find a solution. If we’re playing that game, why not also factor in the social implications of woframite mining in the Congo (a major tungsten producing ore) and then infer the percent contribution of incandescent lighting to the DRC conflict? I don’t have the data in front of me, but I’ve worked with mining industry and am willing to hang my hat on the notion that at the level of ore production, processing, and shipping, incandescent and CFL mercury release during materials production is equivalent. That leaves us with the manufacture of CFL’s and incandescents. It would have to be an extremely inefficient process for CFL manufacture to release more mercury than burning an incandescent.

      Currently the best available evidence shows that CFL’s are better for the environment. Show me evidence that disproves that and I’ll happily switch sides.

      I’m not sure what’s unproven about my hypothesis or why you think it should just be dismissed. If you want to use a product with known environmental impacts, that’s fine, but if better alternatives are available, why shouldn’t you have to shoulder the difference between the two? Releasing mercury into the environment affects us all.

    • “Currently the best available evidence shows that CFL’s are better for the environment. Show me evidence that disproves that and I’ll happily switch sides.”

      No you won’t because you’re a biased industry shill. The evidence and facts are out already: you don’t care because you are biased and financially profiting from donations from the so-called “eco-lighting” industry.

  6. If I was talking about irrelevant unknowns like wolframite mining you might have a point, but I was talking about mercury mining which seems pertinent. It could be that mining mercury for CFLs releases no mercury into the environment, or it could be a significant amount. You haven’t claimed that mercury mining creates zero mercury pollution, so I assume some amount of that pollution should be assigned to CFLs. How then can you claim that CFLs release less mercury into the environment when you admit that you don’t know what the actual figure is?

    I’m not dismissing your hypothesis, nor am I saying the opposite is true. But it’s not science to just say trust me that the mercury I can’t account for is insignificant. As for shouldering the impacts, that could be an interesting discussion though I’d guess many people in the world might point out that we don’t have a lot of moral high ground when it comes to energy consumption and known environmental impacts.

    • No, we’re talking about the relative impacts of CFL’s and incandescent bulbs. Mining woframite is an essential first step in the production of incandescents, so if you claim we can’t ignore the impacts of mercury mining, than we also can’t ignore the impacts of woframite mining. I haven’t claimed that mercury mining produces zero impact, just that I suspect that at the production level, the impacts of production of CFL materials and incandescent materials is probably a non-zero, but similar number.

      Or, if you want to take a individual-centric view of the world, we can’t, as individuals, regulate mining consequences in other countries, but we can control for our own impacts, thus, as far as an individual’s ability to decrease their environmental impact, the buck stops at energy use.

    • I was restricting my comments to the topic of mercury, so unless there is mercury pollution associated with wolframite mining, it wasn’t relevant. The relationship between wolframite mining and the DRC conflict was even less relevant. But if you’re comparing the overall environmental impacts of CFLs and incandescent bulbs then the environmental impacts of wolframite mining should be included.

      From what I’ve read the energy for CFL production is, or was at the time, almost 10 times higher than for incandescent bulbs, but when adjusted for the assumed longevity of CFLs there’s not much difference. Since neither of us has any figures on mercury pollution at mines or factories, the amount of mercury pollution due to the use of CFLs is still unknown.

      I don’t know what to make of your last paragraph. From your previous comments I thought you disapproved of an individual centric world view. Besides, if we assume that someone doesn’t care about pollution in other countries, then why assume they want to decrease their environmental impact on a national scale especially if that reduction comes with the possibility of a small mercury spill.

      According to an article at Environmental Science & Technology (http://pubs.acs.org/doi/full/10.1021/es8025566), a 2008 study by researchers at Yale showed that “cleaner-powered places like California and Norway would do better to stick to incandescent bulbs when it comes to reducing mercury.”

    • Philosophically, I think we’re in agreement that at some point an arbitrary cut-off has to be made when trying to assess environmental impacts.

      If you decide to cut it off at the direct environmental consequences of each bulb, than incandescents win. If you look at the indirect costs of both the physical product and the resources needed to make than product work, than CFL’s win. Further down the hierarchy, you can look at comparisons between the relative environmental impacts of the vertical process from mineral extraction through production and use – currently data deficient. At the extreme end, you have to look at the sum total social/economic/environmental impacts involved in each – data extremely deficient.

      We both agree that it would be great to know the impacts from mining. Even better if a team of social scientists, economists, and environmental toxicologists want to dedicate their careers to conducting a totally comprehensive assessment, that would be nice.

      Where we seem to differ is that I’d rather work with the best available data and modify as more becomes available, while you’d rather not make a decision until all the data are in. Both are perfectly reasonable approaches, but I fear you may be waiting a long time.

      Please note that working off the best available data does not mean we stop collecting data.

    • Admittedly, there are likely to be unknowns, estimates and assumptions, but before having a discussion about how significant those things are, I have to know what they are. At present, I don’t know any of that or what evidence supports your statement that CFLs are better for the environment.

  7. Dear Southern Fried Scientist, I have to comment on some of your logic here. mercury is not the only b ad thing about Compact Fluorescents but let’s start there. One major problem with your maths is that the ballast factor of typical CFLs is around 0.5. Crudely speaking that means that you have to put twice as much energy into the generating system to get the rated wattage out. Of course it isn’t as simple as that but as we are looking at the simplest argument for your figures you need twice as much coal per kilowatt hour for your CFL therefore your mercury figures should be 7.5mg for the CFL and 6.81 for the incandescent lamp. Now if we look at coal firing not all the mercury is released into the atmosphere a fair proportion remains in the fly ans and soot that are collected and reprocessed or used so that the mercury is contained. Your CFL will more often than not end up in landfill, currently less than 10% are recovered for recycling, of which more in a moment. When the CFL gets in the landfill the chances of it not being broken after compacting waste in the collection vehicle or in the site are negligable. In the landfill there are lots of microbes that will digest the mercury whether gaseous, liquid or mixed with phosphors and excrete it as Methyl Mercury that is water soluble and about 20 times more poisonous than gaseous or liquid Mercury. This ends up leaching out to the ecosystem and can never be recovered!

    The lamps that do get recycled do not provide any material suitable for re-manufacture into lamps. The cost of Mercury extraction is relatively high so now many of the mercury contaminated materials are containerised and dumped as contaminated waste. The plastics are not recoverable as they contain brominated fire retadants to stop the things bursting into flames when they overheat and fail. The glass is always contaminated to the extent that it cannot be sold for re-use and is given away as material for road fill or conversion to glass wool, so there is little recovery of materials at all. Add to this the fact that the majority of CFLs are made in China or other far eastern countries requiring new raw materials including mined cinnebar for Mercury. This causes devastation in the areas of China where it is mined, go look up the internet for examples and numbers for this! As for “not harmful” CFLs talk to anybody who has UV sensitive skin conditions. Talk to people who suffer from Migraines. Talk to people who care for Autistic Children, all of whom do suffer from specific effects from any fluorescent lights let alone those brought into the home.

    CFLs are a very poor product for domestic lighting and offer much less environmental benefit than is claimed. If you want documented conspiracy theory check out the Greenpeace response to the report they commissioned way back in the 90’s as available on my website. Really the biggest conspiracy is just stupidity by politicians looking for an easy low cost (to them!) campaign to make the voters think that they are actually doing something about climate change. Forcing people to change to CFL is exactly what they found that will impact everybody. There will be long term problems with this not the least is the total failure of this policy to really affect the energy use and green house gas production.

    Kevan Shaw Director of Sustainability for PLDA

    • Kevin, I’m not usually one to use the “you said something completely wrong, therefore why should I trust anything you say” argument, but I find myself without a lot of time.

      Your explanation of ballast factor is wrong.

      You said: “the ballast factor of typical CFLs is around 0.5. Crudely speaking that means that you have to put twice as much energy into the generating system to get the rated wattage out. Of course it isn’t as simple as that but as we are looking at the simplest argument for your figures you need twice as much coal per kilowatt hour for your CFL”

      A lower ballast factor does not mean that it takes twice as much energy to light a bulb. It doesn’t mean that at all.

      The Lawrence Berkeley National Laboratory explains:
      “Ballast factor is not a measure of energy efficiency. Although a lower ballast factor reduces lamp lumen output, it also consumes proportionally less input power.”

      (Source: http://ateam.lbl.gov/Design-Guide/DGHtm/ballastfactor.htm)

  8. PS I forgot to mention that according to the research done for the European Commission the materials environmental impact of a CFL is 12 times that of an incandescent. This is available from the EUP4light.net website if you read through the comparative analysis in the Ecoreport spreadsheet tools for environmental impact of the different limp type.

    Kevan Shaw

    • There’s a blog post regarding it on this site. Look it up. As long as you’re looking things up, look up some actual journal articles regarding methyl-mercury. There are scads of them. Any of them are good places to start. This was the first one I could find, I work under one of the author’s coworkers. It’s a little dense, but the take-home message is do not mess with MeHg. Maybe read the abstract, skim the intro and then skip to the discussion, would be my suggestion, unless you feel like wading through lots of biochem.

      http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2265788/

  9. @Sam Thanks, I didn’t know that methyl Mercury had such a direct effect on fishes, I was aware that many fish sequester mercury in their fat stores and humans particularly value fatty fish such as Salmon and Tuna for Omega 3 fatty acids (and they taste good!) consequently increasing human exposure to mercury compounds. The heavy sell on CFL that will largely end up in landfill and the increasing demands for new mercury production are somewhat counter intuitive when in the last decade we have done so much to reduce the number of commercial mercury containing lamps ending up land filled. This is one of the major disconnects in the whole sorry story of the incandescent lamp ban.

    Kevan Shaw

  10. I tried to do the math for how much mercury is put out by all of our lighting in a year:

    29 E15 wh *0.02 * 0.012 mg/kwh *0.001 kw/w = 7 E9 mg = 7 metric tons

    According to the NY DEC, last year Americans purchased 400 million cfls.

    400 E6 cfl * 4 mg/cfl = 1.6 E9 mg = 1.6 metric tons

    How much mercury was emitted in the process of mining, making and selling these cfls? Good question, I have no data, but I would be surprised if it were enough to counter the increased efficiency. (I am often, however, surprised…)

    These numbers should be compared with something in excess of 100 metric tons for annual US emissions of mercury. Will more efficient lighting result in fewer power plants emitting less mercury? Or will the decreased demand for electricity for lighting only make it more affordable for other uses?

    • Otto,
      Did you realize that if your figure of 0.012mg/kWh is used in Southern Fried Scientist’s calculations instead of 0.0234mg/kWh then CFLs no longer win out in what he called “…our most conservative estimates…”?

    • Skeptic,

      Do you realize that .012 mg Hg is already accounting for 50% power produce by coal (it’s half of 0.0234 mg Hg)? It doesn’t change the “conservative calculation” at all (actually it slightly favors the CFL’s because it’s rounded up). Nice try though.

    • SFS,

      Maybe I’ve still got this wrong, but looking back at your post I think the 0.0234mg Hg figure was wrong to start with because coal burning plants don’t put out that much Hg. I should have noticed that if the “…amount of mercury released by a coal burning power plants…” was 0.0234 mg/kWh then there would be no reason to divide the resulting answer in half. The answer had to be divided in half because the actual estimate is 0.012 mg/kWh. So while using 0.012 mg/kWh hours is correct, inserting it into your calculations in place of 0.0234 mg/kWh is not.

      I was just looking at an Energy Star FAQ which uses 0.012 mg/kWh Hg, but significantly less Hg for landfilling (0.6mg Hg) This time using 14% emission instead of the 11% figure they used elsewhere. I don’t recall seeing those numbers anywhere else, but if their figures are accurate then, assuming longevity and power coming from a coal power plant, incandescent bulbs don’t even come close to CFLs for mercury emissions during use and disposal.

    • You definitely are reading that wrong. In my “most conservative estimate” I used the maximum amount of mercury possible (0.0234 mg Hg is produced by coal plants), and the amount of energy produced by coal burning plants (50% of our energy comes from coal). The national average is 0.012 precisely because not all our energy comes from coal burning plants. You cannot simply decide to weight one variable and then compare it to the unweighted variable, because, of course, I’m also assuming total mercury release from every CFL and every CFL being the most mercury heavy variety. The numbers you should be comparing if you want to look at weighed (not maximum potential) outcomes are provided by the EPA (and linked to in the above article):

      CFL’s
      National Average mercury Emissions – 0.012 mg kWh
      Mercury from electricity use – 1.2 mg
      Mercury from Landfilling – 0.6 mg
      Total – 1.8 mg

      Incandescents
      National Average mercury Emissions – 0.012 mg kWh
      Mecury from electricity use – 5.8 mg
      Mercury from landfilling – 0 mg
      Total – 5.8 mg

      In which case incandescents get destroyed even more so than my most conservative estimate. If you want to argue that mining has great impact, that’s perfectly valid, but there’s no way short of cherry picking the numbers to put incandescents on top looking at just energy use and disposal.

    • At first I was confused by your last paragraph with the cherry picking reference, but after rereading what I wrote I realized that my last sentence was very poorly constructed. Poor sentence structure makes it appear I’m saying the opposite of what I meant. CFLs have substantially lower Hg emissions in the Energy Star article, and CFLs would still be lower if the whole 4mg Hg in the CFL was added since it would be CFL 5.2mg and incandescent 5.8mg. Though to be clear I’d better say that I’m not suggesting the 4mg/bulb should be added.

  11. In comparison to their incandescent counterparts, CFLs emit approximately the same amount of visible light and last 8 to 15 times as long and provide significant energy savings. The use of more efficient lighting options, such as CFLs, is one of easiest and lowest-cost ways for the nation to reduce electricity use and greenhouse gases. Many people are concerned that the small amount of mercury contained in CFLs makes them an environmentally unfriendly option. However, incandescent bulbs ultimately result in greater mercury exposure than CFLs because they consume much more power and require more power generation. Since mercury is a byproduct of burning coal, coal-fired power plants are a larger source of mercury pollution than the mercury content in the CFLs.

    Although CFLs and fluorescent lamps result in less mercury pollution than incandescents, it is still important to store and transport used lights to a recycling facility in a packaging configuration proven to contain mercury vapor. Only then are these products truly green lighting solutions. Find out more here: http://vaporlok.blogspot.com.

  12. The pro-CFL West is responsible for China restarting mercury mining and all the worker-exposure and environmental damage that goes along with that. Way to go West, wreck China’s environment and then play holier than thou to then on the environmental question too!

  13. Several comments by John have been removed as per Rule 3 – parroting. Please not that this is not a shouting match and excessively repeating the same point is tedious, boring, and contrary to an open dialog.

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