Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Why LEDs Don't Beat CFLs Even Though They Should 685

TaeKwonDood writes "LEDs don't beat CFLs in the home yet, but it's not simply because PG&E is getting rich making people feel like they are helping the environment buying CFLs made in China that are shipped to the US using a lot more fossil fuels than they save. It's a problem of indication versus illumination. However, some new discoveries are going to change all that."
This discussion has been archived. No new comments can be posted.

Why LEDs Don't Beat CFLs Even Though They Should

Comments Filter:
  • by daveschroeder ( 516195 ) * on Tuesday December 30, 2008 @07:59PM (#26273873)

    LEDs are not traditionally used for illumination not only because of the costs of LEDs, but because of the complex optics required to distribute the light. it's rare to see LEDs used for illumination, though it is making an entrance for some applications, like flashlights [] and even headlamps []. As LED prices continue to come down and LED optics technology improves and cost stabilize, conventional LED lamp retrofits will become commonplace. Take a look at LEDtronics [] for some examples.

    • by Anonymous Coward on Tuesday December 30, 2008 @08:08PM (#26273941)

      Did you notice all the LED xmas lights this year?

      • Re: (Score:3, Insightful)

        by ikkonoishi ( 674762 )

        Yeah they looked awful. LEDs produce too much light in the more violet spectrums. Making each of them look like they are surrounded by a purple/black aura to me. The old style lights are a lot warmer and more inviting.

    • by BlueParrot ( 965239 ) on Tuesday December 30, 2008 @08:11PM (#26273973)

      Sorry but I don't buy the optics issue. It really can't be THAT hard to put a lens or reflector in the armature and point multiple LEDs in different directions. If anything LEDs should be preferable to incandescents because it is easier to take something very directional and spread the light than it is focus the light from a divergent source. I think the main reason LEDs are not popular yet is cost and "it's not what I'm used to". Seeing the type of crap people will buy even when there are better alternatives I simply don't believe that something as sophisticated as the beam profile of an LED will be a huge issue.

      • Re: (Score:3, Insightful)

        by kaizokuace ( 1082079 )
        yea it's all marketing. People buy what they hear about. It's the truth and I haven't seen any LED light fixture ads anywhere!
      • by Anonymous Coward on Tuesday December 30, 2008 @09:06PM (#26274465)

        It's actually harder than it seems. Just imagine trying to light up a room using a laser. How hard can it be, right? LEDs are *very* directional too.

        It takes far more than a simple lens, or a simple reflector to manage to illuminate a workspace evenly using them. Reflectors work fine for incandescent/fluorescent and such non-directional light sources.

        That's why we see LEDs thrive in many applications like flashlights and traffic lights and not others: those require directional light.

        And even if you found a great way to do it, it would still add [likely significant] cost, and likely a fair amount of weight, if using optics. It would probably look like a huge catadioptric lens of a lighthouse (well, the inverse job, but a huge chunk of glass is what I meant). The best I've seen so far, is using a large number of lesser power LEDs...

        • by lessthan ( 977374 ) on Tuesday December 30, 2008 @09:36PM (#26274737)
          A glass of cloudy water would do what you ask, quite easily.
          • please consider voting parent to 'insightful', or at least 'interesting'

          • by ppanon ( 16583 ) on Tuesday December 30, 2008 @10:09PM (#26275083) Homepage Journal
            For something more compact and less wet (a consideration around compact electrical devices): a diffraction grating. Add a glass frosting on top of a couple of layered diffraction gratings to make the light more evenly diffuse.
            • Re: (Score:3, Interesting)

              by Anonymous Coward

              For something more compact [...]: a diffraction grating. Add a glass frosting on top of a couple of layered diffraction gratings to make the light more evenly diffuse.

              A similarly simple/cheap solution would be to use a non-perfect parabola or convex mirror. The LED beam, though directed, is not infinitely thin. Therefore, putting it at the "focal" point of a shiny, non-perfectly parabolic surface or aiming it towards a matte convex mirror would also do the trick.

          • by 404 Clue Not Found ( 763556 ) * on Wednesday December 31, 2008 @05:28AM (#26277933)

            It does work -- somewhat! Here's proof [], a LED camping lantern that uses a standard Nalgene water bottle to diffuse its light.

          • Not practical (Score:3, Insightful)

            A glass of cloudy water would do what you ask, quite easily.

            Sure, as long as you don't mind destroying the energy efficiency that was the original reason for using LEDs in the first place.

            It's definitely not trivial to take a directional light source and shape it so that the output is directionally uniform. I'm a cyclist, and I use LED lights for riding at night. They're just now getting to the point that they're reasonably priced, with decent power, and with a decent beam pattern in maybe a 10-15 degr

        • Re: (Score:3, Informative)

          by nwf ( 25607 )

          I suspect it's easy to make uniform mono-chromatic light, but people want white LEDs which have phosphor to convert part of the blue to yellow. That needs to be uniform and likely complicates matters. Notice that most LED flash lights have a bluish center, even the pricey Maglites suffer from this. A good halogen bulb is still much more uniform, which makes it more useful when trying to find things in the dark (no patterns imprinted on the scene from your light.)

          I got good results by drilling a hole in a pi

      • by petermgreen ( 876956 ) <[ten.knil01p] [ta] [hsawgulp]> on Tuesday December 30, 2008 @09:16PM (#26274551) Homepage

        The experiance of everyone I know who has tried LED light fixtures is they simply don't have the ability to decently light a room (whether this is due to thier being simply less light output or whether it is some other characteristic of the light I don't know) while CFLs do. They are also FAR more expensive than CFLs.

        • Re: light a room (Score:4, Insightful)

          by Dare nMc ( 468959 ) on Wednesday December 31, 2008 @12:26AM (#26276351)

          Thats definitely per cost, not per watt preventing room lighting. I suspect it is the same as CFL, many manufactures overstate the "equivalent light" factor causing a perception of dimmer. I bought led lights for my aquarium, just the 4 watt night lighting lights up 2 rooms ( not reading wise, but way too bright for a night light, the water diffuses the light nicely)
          The directional nature also means to be truly efficient you would want more locations, the lasts (nearly) forever nature would tend to lead to a permanent mount.
          So saving the cost of running thicker wires, fixture boxes, fixtures, 5 amp switches, etc should make LED lighting affordable for new houses/additions/remodels fairly soon.
          (Especially for warm locations where you pay for all heat sources double, with AirCond)

      • Re: (Score:3, Insightful)

        by kimvette ( 919543 )

        Seeing the type of crap people will buy even when there are better alternatives I simply don't believe that something as sophisticated as the beam profile of an LED will be a huge issue.

        "Better" without specifying or considering criteria is subjective. IMHO a Ferrari is a better car than a Porsche, but by what criteria? I can also say that the Porsche is better than the Ferrari, and not be contradictory because I'm considering different aspects, i.e., am I referring to asthetics, raw performance, comfort, r

    • by tuxgeek ( 872962 ) on Tuesday December 30, 2008 @08:31PM (#26274129)

      Although I agree with some points of your post, most of your belief is not quite accurate. LEDs now make the best flash light illumination, and the power drain on batteries is minimal. I've been using LED headlamps for years, so this is nothing new, as your post implies.

      The problem with them being used in homes is that they direct their illumination to a specific spot. This is not a bad thing though. I've recently seen them configured as spot lamps. Perfect for recessed lighting.

      The optics in LED technology can easily be modified to diffuse light to make a great replacement for CFL & incandescent. Give it time.

    • Re: (Score:3, Interesting)

      by Enderandrew ( 866215 )

      I've heard that a room lit by LED doesn't look as natural, but then again, I haven't seen LED light fixtures to test for myself.

      • by icebrain ( 944107 ) on Tuesday December 30, 2008 @08:45PM (#26274261)

        Disclaimer: I have no experience with LED "lightbulbs" like those in TFA, only LED flashlights

        To me, the biggest hangup on going to LED lighting from CFLs would be the spectral issue. In my experience, "white" LEDs don't actually put out true white light, but rather several distinct wavelengths that look approximately white to human eyes. IIRC they lose some definition with red/green. Not as big an issue for a flashlight, but in room lighting I'd kind of want all the colors showing up. This may very well be solved by now, however. I don't know.

        • by Orange Crush ( 934731 ) on Tuesday December 30, 2008 @10:50PM (#26275537)
          CFLs have to address the same problem. Mercury vapor by itself glows in the UV range. The rest is done with phosphors, as in "white" LEDs. It's just a matter of getting the right "blend" of phosphors that balances efficiency with a decent color range. Of course, you're never going to get the full spectrum of an incandescent source--be they lightbulbs or the sun. But they'll eventually get pretty dang close.
    • Re: (Score:3, Interesting)

      by Psion ( 2244 )
      For about a year now, my home office has been lit with LEDs. I have 3 watt units on goosenecks that I switch on and twist for directed illumination, and arrays of RGB units that have tunable color. They all feed through the UPS that protects my desktop, and consumes, at most, a little over twelve watts (when all lights are on and RGBs are set to white light). I'm quite happy with the effect and level of illumination. The only downside is that the rest of the room is relatively dim, lit only with reflected l
  • Riiight (Score:5, Insightful)

    by Valdrax ( 32670 ) on Tuesday December 30, 2008 @08:03PM (#26273899)

    CFLs made in China that are shipped to the US [use] a lot more fossil fuels than they save.

    'Cause incandescents are all made in the US and don't share nearly the same shipping costs.

    • Re:Riiight (Score:5, Insightful)

      by rolfwind ( 528248 ) on Tuesday December 30, 2008 @08:21PM (#26274047)

      But what if you had to ship 6 lights for every one due to lifespan differences?

    • Re: (Score:3, Informative)

      Until earlier this year (when they stopped production in favor of CFLs), GE was still manufacturing their incandescent bubls in the US.

  • by PontifexPrimus ( 576159 ) on Tuesday December 30, 2008 @08:08PM (#26273939)
    Errr... could we have some actual numbers for that? Are we seriously asked to believe that the energy saved by a metric ton of CFLs over their lifetime is less than the cost of a one-trip transport on a freighter? Or is that just another bitter remark aimed at those silly little hippies who want to save their pwecious planet and their breathable atmosphere and their clean water?
    • It is amazing what hate there is for anything new. More amazing because many of us have made money off the next new thing. What is even more embarrassing is the innumeracy illustrated in the FUD.

      Let's say that you do pay extra for the incandescent light bulb made in the US. Let's further assume that number of times a user has to drive to the store and replace the incandescent light bulb is compensated by the increased mass, and chemicals, in the CFL. Even with that, one can't ignore the basic physics

      • Speaking of caves... (Score:3, Informative)

        by mad.frog ( 525085 )

        Actually, caving (don't call it spelunking []) is one of the areas that modern LEDs have absolutely taken over: the combination of efficiency, durability, longetivity, and small package size have completely replaced incandescent options (e.g., [])

        Old-time carbide lamps still have limited application, mostly in giant caves and/or extremely long & cold expeditions, but Fluorescent has always been far too fragile in terms of packaging to warrant consideration.

  • Seriously? (Score:5, Insightful)

    by ergo98 ( 9391 ) on Tuesday December 30, 2008 @08:10PM (#26273959) Homepage Journal

    You're seriously trying to claim that the savings of CFLs are offset by shipment? Really?

    I would go into the obvious math or the economics, but honestly this is just simply too stupid to even deserve further comment, except that it is a completely asinine, baseless statement that I'm sure will be picked up and repeated by a lot of ignorant contrarians.

    • Re:Seriously? (Score:5, Insightful)

      by Goaway ( 82658 ) on Tuesday December 30, 2008 @08:51PM (#26274333) Homepage

      It's the hip new anti-environmentalist meme. Anything that is supposed to lessen emissions actually increases them because you have to build it!

    • Re:Seriously? (Score:5, Informative)

      by sfbiker ( 1118091 ) on Tuesday December 30, 2008 @10:11PM (#26275107)
      I'll take a stab at the math.

      A 20' container is approx 19' x 7' x 7' or 1.6M cubic inches (it's a bit bigger, but I left room for pallets, etc).

      If a CFL + packaging is 3" x 4" x 6" = 72 in^3 then you can fit around 22,000 of them into a 20' container

      This site [] claims you can ship a 20' container from China to the US for $3800 USD

      Let's say that 75% of the shipping cost goes toward fuel, the rest goes to labor, paying off the ship, container rental, etc. Sounds reasonable.

      I'm going to use Diesel for the energy calculations. I know that ships run off bunker fuel, not diesel, but I have to think that the cost per unit of energy for bunker fuel is cheaper than diesel since it's less refined, so by using Diesel I'm being conservative. Right now you can buy diesel for under $2/gal, so with 75% of $3800, we can buy 1425 gallons of diesel.

      Diesel has 38 MJ [] of energy per liter (143 MJ/gal), or 40KWh according to the units command.

      So, each light bulb uses 40KWh / 22,000 = 1.8 KWh (1800 Wh)of energy

      A 29 Watt CFL can replace a 100 Watt incandescent bulb, so that's a 71 watt savings... 1800Wh / 71 W = 25 hours

      Sooooo....a CFL will save the energy used to ship it in about 25 hours of operation. CFL's are supposed to last 5000 hours, so over its lifetime, it will save over 200 times more energy than used to ship it. (of course, this is only this shipping energy, and ignores the extra energy that it took to manufacture the CFL it as compared to an incadescent. I don't know how to do that math).

  • by wjh31 ( 1372867 ) on Tuesday December 30, 2008 @08:14PM (#26273991) Homepage
    just my wallet. I got a set of LED GU10 bulbs for the flat because when we got in there were two fittings of 4x50W bulbs each, and with the energy saving from some LED replacements (~£10 for 4 at ~2W ea, normally ~£5ea but i found a deal) easily paid the difference, especially since i was having trouble finding CFL replacemetns. However they definately give off significantly less light than the 50W halogens, which is fine most of the time as i prefer a dimmer light usually, but can be a little frustrating if i find myself needing a little extra to look for something, The light is alot 'whiter' which took a couple of days to get used to but is fine now. They are also very directional, they light up one area very well, but are quite poor outside that area, so fine if you are after light in a particular area (they are often advertised as for lighting up some piece of art you want attention drawn to) but not so good if you want to illuminate a room.
  • by rolfwind ( 528248 ) on Tuesday December 30, 2008 @08:18PM (#26274015)

    an directionality. It's hard to beat CFLs and moreso some good quality fluorescent tubes get slightly more lumens per watt (although I saved 100 watts per hour in the kitchen - 200 instead of 300- by going with directed CFLs that shine line exactly where needed vs previous central flourescent tubes that were lighting from the center trying to sloppily spill light everywhere).

    Since every Home Depot now takes any CFLs, the disposal is actually better than fluorescent tubes. Considering most electricity comes from coal, you prevent mercury release in the air vs incandescents. And no, you don't need a specialized clean up crew if a CFL breaks: []

    Except for the oven, fridge, and flashing lights - CFLs are appropriate for most applications.

    I would love to have LEDs. But they need to raise their efficiency. They don't generate heat as such, but AC->DC conversion does, index of refraction of the casing material presents a problem, as well that leds don't generate white light by themselves (they use phosphor?) and all that reduces the light given off.

    It would be cool if those were solved one day, where they got near 90% theoretical max lumens/wax (683 lm/wt), where a 3 watt LED would give off the same light as a ~100 watt incandescent or ~23 watt CFL. Even 150 or 200 lm/wt would be a revolution. But it will take 5-10 years I suppose.

    • by evanbd ( 210358 ) on Tuesday December 30, 2008 @08:38PM (#26274183)
      Note that you can't get white light at 683 lm/W. The lumen has an efficacy curve approximating the human eye response. 683 lm/W implies a perfectly efficient monochromatic 555nm (green) light. An ideal black body is limited to about 95 lm/W; however that's not the ideal output either (the UV and IR components aren't helpful). Actual efficiency for white light is probably limited to 100-200 lm/W, and will depend on how green you allow your white light to be.
    • Re: (Score:3, Interesting)

      by aaarrrgggh ( 9205 )

      There is actually more to the equation than lumens/watt. You have to look at the effectiveness of the light produced for the task and fixture at hand. My office desk lamp is incandescent, but is more efficient than the fluorescent fixtures because it puts the amount (and quality) of light in the place that I need it.

      LEDs are great in applications where you really just need an accent and 1-5W of light is adequate. Mainstream CFLs are 11-42W in contrast. Things like lighting a corridor which could either

  • Uh (Score:5, Insightful)

    by nightfire-unique ( 253895 ) on Tuesday December 30, 2008 @08:37PM (#26274167)

    Wow. Way to sneak in that lie under the radar. Politically motivated, or just simple ignorance?

    In any case, no, the manufacturing and transport of CFL bulbs absolutely does not generate more CO2 than that saved by using them (assuming coal/natural gas powered, the only logical comparison in this case). Let's run some simple numbers.

    Assuming an average 60-watt equivalent (12 watt nominal) CFL bulb with a lifespan of 10,000 hours, it will draw 120kWh over the course of its life. The 60-watt incandescent, if it lasted as long, would draw 600kWh. Of course, it doesn't last as long, but rather an average of 1/5 as long.

    So the savings are roughly 480kWh for an 800lm fixture. That's the equivalent of over 400 liters of gasoline burned in an internal combustion engine, and that doesn't include the fuel used building, shipping and shopping for replacement incandencents, which as mentioned burn out far more frequently.

    Now for some logic. How is it that a bulb which apparently requires >480kWh of energy to build/ship ($48 at $0.10/kWh) sells for a few dollars? Hint: it doesn't require >480kWh of energy to build/ship, or anywhere near that.

    CFLs offer a massive net efficiency gain, and by extension, a net reduction in CO2 emissions. Even factoring in disposal costs at 5 times the manufacturing cost (silly), CFLs are a net win. So please don't spread that tripe!

  • Shipping Costs (Score:5, Informative)

    by bxwatso ( 1059160 ) on Tuesday December 30, 2008 @08:37PM (#26274169)
    If a 25W CFL replaces a 100W incandescent bulb, and the CFL lasts 8000 hours, it will save 600 KWHrs of energy.
    If a shipping vessel can hold 35,000 tons of cargo and the shipping weight of a CFL is 1/2 pound, the vessel can hold 140 million bulbs. Of course there is not enough space for them all, but they can ship with heavier items, and I am assuming costs are allocated by weight.
    If a 7,000 mile journey burns 875 tons of fuel, or 15.75 million gallons, then each bulb is allocated .11 gallons of diesel for the journey. That is about 6 KWHrs of energy.
    Therefore, the shipping costs don't even come close to negating the energy savings.
  • by John3 ( 85454 ) <(moc.sllenroc) (ta) (3nhoj)> on Tuesday December 30, 2008 @08:39PM (#26274191) Homepage Journal

    The vast majority of light bulbs are imported from China. Incandescent, halogen, fluorescent, CFL, you name it, it's likely made in China. I own a hardware store and have watched over the years as production of GE bulbs has shifted from the US to Mexico to China. It was interesting to note that some of the specialty bulbs (for example, a bulb called Lumiline []) had very high defective return rates when produced in Mexico, so GE moved manufacturing back to the US for a while until the bugs were worked out.

    Anyway, this transportation cost objection is bogus IMHO. Incandescents weigh slightly less than CFL's, but they take as much "cube" space in container loads so the cost to transport is probably similar to CFL's.

  • by roc97007 ( 608802 ) on Tuesday December 30, 2008 @09:01PM (#26274419) Journal

    I really want to switch to LEDs. I've become disillusioned with CFLs in recent years. The very first two CFLs we ever purchased, in the mid-nineties, -- my wife's reading lamp and the hard-to-reach light in the stairwell -- are still working. But in recent years (since maybe 2002) I've had a remarkable number of failures, often in the first month of use, and I rarely see more than a couple years of service. Oddly enough, I get longer service from the outside lights, which should be the harshest environment. The indoor CFL overhead lights (except for that stairwell light) last about a year. The worst service is from the CFL globe lights over the mirrors in the two bathrooms. I lose about one a month, and recently I've started replacing them with incandescents as they burn out.

    I think part of this is due to putting CFLs in environments where they do not thrive -- anywhere you have heavy on/off duty cycles like a bathroom or occasionally used overhead. But I wonder also if CFLs in general haven't become (at least in part) victim to "value engineering", IE, making them as cheap as possible.

    But anyway, what worries me about LEDs is that although they *should* give longer life, (50K hours vs 15K for CFL and 1K for incandescents) they apparently don't, judging by the LED array stoplights that have been put in all around the city. It's difficult to find one that doesn't have large parts of the array completely out or blinking madly. Around Christmas I noticed that some of them had been replaced with conventional bulbs. Looking at the technology, LEDs should do better, but it's all about implementation.

    • Re: (Score:3, Insightful)

      by rrohbeck ( 944847 )

      I guess it's not the LEDs themselves, but you need electronics to down transform and rectify the AC. Now if that's left to the lowest bidder you can expect high failure rates. It's probably the same with the CFLs. Everybody is used to incandescents to fail all the time so it doesn't make a difference if they're crap.

    • Re: (Score:3, Informative)

      by Lumpy ( 12016 )

      They do better if they are not half assed. A cheap PAR60 LED flood should cost you about $45.00 anything less than that is trash and will die. problem is Americans in general are really cheap bastards and flip out when they see a $45.00 light bulb.

      So what you can buy are really really low grade crap that has not been tested and probably are full of cold solder joints. your municipality is also being cheap bastards and buying the cheapies instead of the $225.00 lamps they SHOULD be buying for those stopl

  • Strange... (Score:5, Interesting)

    by knarf ( 34928 ) on Tuesday December 30, 2008 @09:02PM (#26274429) Homepage

    I've been using CFL's since at least 1995, probably a lot earlier. Starting with the big Philips 'jam jar' types which lasted more or less forever - I still have some of the first lamps I bought, now more than 15 years old, they still work - and gradually moving to the more recent folded tube and even more recent incandescent form factor ones I have yet to see any trouble with them. They *just work*, save a *lot* of power and hardly ever burn out.

    In other words, I completely fail to grasp the reluctance to change over, leading even to conspiracy theories and pseudo-science arguments against these dependable light sources. They may not be the best choice for all applications but they are a good match for most.

    • I've been using CFL's for about four years, some indoor and some outdoor.

      CFL issues:

      1) None of the CFL's I have used last as long as the incandescents they replace. One outdoor fixture in particular goes through about three CFL's a year whereas before I used to be able to leave a bulb in a few years.

      2) Color is not great.

      3) Lumen output is lower, usually too much lower.

      4) Dimmable CFL's are hellishly expensive. I miss dimmable lighting, which often I turn low enough that I doubt a CFL would be saving me a

  • by mosb1000 ( 710161 ) <> on Tuesday December 30, 2008 @09:02PM (#26274433)
    The little snippet at the end of the post if off-base, but it is good to keep in mind that LEDs are significantly more environmentally friendly nonetheless. They last a long time, years and years, and they are very durable. They don't require toxic chemicals, and they are more energy efficient than CFLs.

Today is the first day of the rest of your lossage.