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LED Lighting As Cheap As CFLs Invented 553

Posted by Soulskill
from the bright-ideas dept.
mcgrew writes "New Scientist reports that a British team has overcome the obstacles to cheap LED lighting, and that LED lamps as cheap as CFLs will be on the market in five years. Quoting: 'Gallium nitride cannot be grown on silicon like other solid-state electronic components because it shrinks at twice the rate of silicon as it cools. Crystals of GaN must be grown at 1000C, so by the time a new LED made on silicon has cooled, it has already cracked, rendering the devices unusable. One solution is to grow the LEDs on sapphire, which shrinks and cools at much the same rate as GaN. But the expense is too great to be commercially competitive. Now Colin Humphreys's team at the University of Cambridge has discovered a simple solution to the shrinkage problem. They included layers of aluminium gallium nitride in their LED design... These LEDs can be grown on silicon as so many other electronics components are. ... A 15-centimetre silicon wafer costs just $15 and can accommodate 150,000 LEDs making the cost per unit tiny.'"
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LED Lighting As Cheap As CFLs Invented

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  • Finally! (Score:5, Funny)

    by 1729 (581437) <slashdot1729.gmail@com> on Thursday January 29, 2009 @12:43PM (#26654727)

    Now Colin Humphreys's team at the University of Cambridge has discovered a simple solution to the shrinkage problem.

    Excellent news! Wait, what's this story about?

  • by gfxguy (98788) on Thursday January 29, 2009 @12:44PM (#26654743)

    So I bought a 3 pack of LED lights that were supposed to be the equivalent of 40 watt bulbs...

    A 25 watt incandescent bulb is about 10 times brighter. I was pissed. Might keep me from stumbling in the dark, but it doesn't really illuminate a damn thing.

    I was so hopeful.

    • by gnick (1211984) on Thursday January 29, 2009 @12:48PM (#26654813) Homepage

      I've heard similar reviews from a co-worker who was very motivated to 'go green'. The '40-watt equivalent' turned out to be an over-sized night-light (per her review - I haven't seen it).

      Still, this could be good news. I switched about half-way to CFLs largely to save $$ on electricity, but they're neither as efficient nor as 'green' as LED lights. I priced LED lights but, at the time, they were so damned expensive that it would take ~40 years for the investment to pay itself off. Even if I have to over-rate everything to get the same level of light, it should be better all the way around compared to the current alternatives.

      Still, even though this sounds solid, the ominous 'This should be available in 5 years' always makes me a little cautious.

      • by Erioll (229536) on Thursday January 29, 2009 @12:57PM (#26654953)

        I'm all for getting away from CFLs, as their production alone is NOT environmentally friendly (most of the mercury in the world is mined in China, where HALF of it is "lost" to the environment during production, which means "polluted"), not to mention the ratio thrown out.

        But what about the LEDs? How toxic (or not) are the materials they're talking about? And what about the production of such? And heck, back on the pollution thing, WHERE they are produced makes a big difference, since if it's in China, forget any environmental disposal of chemicals used, whereas if it's in a developed country, it'll probably be OK.

        Not insurmountable problems, but I do want to know how those things will work out.

        • by Idiomatick (976696) on Thursday January 29, 2009 @01:02PM (#26655017)

          If you only replace them at 1/10th or 1/1000th the rate then its unlikely it could be bad for the environment....

        • by danep (936124) on Thursday January 29, 2009 @01:26PM (#26655385)
          Please stop spreading the FUD about the amount of mercury in CFLs, which is negligible. The mercury in CFLs constitutes 0.1% of what we dump into the environment annually, and CFLs contribute far less mercury to the environment than incandescent bulbs. http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf [energystar.gov]
          • by lawpoop (604919) on Thursday January 29, 2009 @02:26PM (#26656307) Homepage Journal
            The problem with CFLs is not the mercury spread into the environment during production, is the spot concentrations of mercury 1. in your home, when you break a bulb, and 2. in the landfill, when people toss them out like regular bulbs, not understanding that these are hazardous waste and need to be disposed of in the proper facilities.

            When you break a lamp, the state of Maine [maine.gov] says "The next time you replace a lamp, consider putting a drop cloth on the floor so that any accidental breakage can be easily cleaned up. If consumers remain concerned regarding safety, they may consider not utilizing fluorescent lamps in situations where they could easily be broken. Consumers may also consider avoiding CFL usage in bedrooms or carpeted areas frequented by infants, small children, or pregnant women. "

            Here's what the EPA says to do if a CFL bulb breaks in your home [epa.gov]:

            Before Clean-up: Air Out the Room

            • Have people and pets leave the room, and don't let anyone walk through the breakage area on their way out.
            • Open a window and leave the room for 15 minutes or more.
            • Shut off the central forced-air heating/air conditioning system, if you have one.

            Clean-Up Steps for Hard Surfaces

            • Carefully scoop up glass pieces and powder using stiff paper or cardboard and place them in a glass jar with metal lid (such as a canning jar) or in a sealed plastic bag.
            • Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder.
            • Wipe the area clean with damp paper towels or disposable wet wipes. Place towels in the glass jar or plastic bag.
            • Do not use a vacuum or broom to clean up the broken bulb on hard surfaces.

            Clean-up Steps for Carpeting or Rug

            • Carefully pick up glass fragments and place them in a glass jar with metal lid (such as a canning jar) or in a sealed plastic bag.
            • Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder.
            • If vacuuming is needed after all visible materials are removed, vacuum the area where the bulb was broken.
            • Remove the vacuum bag (or empty and wipe the canister), and put the bag or vacuum debris in a sealed plastic bag.

            Clean-up Steps for Clothing, Bedding and Other Soft Materials

            • If clothing or bedding materials come in direct contact with broken glass or mercury-containing powder from inside the bulb that may stick to the fabric, the clothing or bedding should be thrown away. Do not wash such clothing or bedding because mercury fragments in the clothing may contaminate the machine and/or pollute sewage.
            • You can, however, wash clothing or other materials that have been exposed to the mercury vapor from a broken CFL, such as the clothing you are wearing when you cleaned up the broken CFL, as long as that clothing has not come into direct contact with the materials from the broken bulb.
            • If shoes come into direct contact with broken glass or mercury-containing powder from the bulb, wipe them off with damp paper towels or disposable wet wipes. Place the towels or wipes in a glass jar or plastic bag for disposal.

            Disposal of Clean-up Materials

            • Immediately place all clean-up materials outdoors in a trash container or protected area for the next normal trash pickup.
            • Wash your hands after disposing of the jars or plastic bags containing clean-up materials.
            • Check with your local or state government about disposal requirements in your specific area. Some states do not allow such trash disposal. Instead, they require that broken and unbroken mercury-containing bulbs
        • by bahwi (43111) <incoming@josephguhli n . com> on Thursday January 29, 2009 @02:02PM (#26655961) Homepage

          More mercury from coal plants used to power incandescent bulbs, 100% of it lost to the environment. Look at whole life, not just one part.

      • by kherr (602366) <`moc.daehteppup' `ta' `nivek'> on Thursday January 29, 2009 @01:30PM (#26655465) Homepage

        The real issue is that all light bulbs really do need to have the rating of lumens. Wattage is power use, lumens is light output (obviously). Saying "40-watt equivalent" is empty marketing speak, no wonder they were disappointing. And then there's the whole light temperature issue, which is very difficult for a consumer to determine.

        For my LED experience, I went with these LED bulbs [theledlight.com] for my chandelier (I was looking for a "25-watt equivalent") and have been very pleased. It may help that it's a cluster of bulbs in my fixture. Considering the lifespan of LED bulbs, I'm willing to pay a lot more per bulb providing the light output falls in the appropriate range.

        • Re: (Score:3, Informative)

          And then there's the whole light temperature issue, which is very difficult for a consumer to determine.

          Especially as color temperature doesn't really tell the story where LEDs and fluorescents are concerned. While incandescent lights are thermal emitters with smooth color spectra, the others are composed of several sharp peaks at different wavelengths, a conditition which doesn't reduce to a single color temperature. It's also much of the reason why the light seems somewhat harsh and unnatural.
          • by dr2chase (653338) on Thursday January 29, 2009 @02:43PM (#26656561) Homepage
            Not so for LEDs; their peaks are substantially less sharp. I verified this both with a physicist, and with a diffraction grating. I took pictures, too. [wordpress.com] One problem you get, is that the "highest lumen" LEDs have a spectrum similar to an arc-welder, and it's not so nice. I used some good-quality neutral-white CREE LEDs for kitchen counter lighting [wordpress.com], and it is quite nice.
      • by rolfwind (528248) on Thursday January 29, 2009 @01:33PM (#26655505)

        I switched about half-way to CFLs largely to save $$ on electricity, but they're neither as efficient nor as 'green' as LED lights.

        How so? Recently, in my local walmart, GE started selling Par20 LED bulbs that were supposed to be 40-50 watt equivalent but for 7 watts produced 200 lumens. That's 28.5 lumens per watt.

        My Feit Electric (Costco) 13w CFLs (60 watt equivalent) produce about 800 lumens. That's 61 lumens per watt.

        A 60w incandescent makes around 700-850, depending on brand. Using the 800 as a comparison, thats 13.3 watts per lumen.

        LEDs may have the potential to be more efficient than CFLs, but it doesnt look like they automatically are. Or am I missing something?

    • by mcgrew (92797) * on Thursday January 29, 2009 @12:55PM (#26654915) Homepage Journal

      Don't lose hope yet. For one thing, a 40 watt incandescant (you didn't specify if what you were replacing was incandescant or CFL) is damned dim to start with. When I used incandescants, the lowest watt bulb I used was usually a 100 watt (60s in closets and in the basement where there's one every fifteen feet), and used 3 way 250 watt bulbs for reading.

      A 40 watt CFL would be damned bright, I don't know if I've ever seen one. Most of my lamps have 27 watt twirley tubes. They vary in intensity, in color, in startup time, and some grow brighter the longer they're on. The one on the front porch won't light if the temperature gets below 0F, the back porch light has lit every time. It's also dimmer and bluer.

      I'm looking forward to these, but when I finally buy one, I'm not going to pick one that says "equivalent to a sixty watt incandescant", I'm going to get one that says it's equivalent to 100 watts, just to be sure.

      • Re: (Score:3, Informative)

        by fizzup (788545)

        A 40-watt CFL is about like a 150-watt incandescent. Here's a link [1000bulbs.com] to a really bright "compact" fluorescent. It's over a foot long.

    • by MobyDisk (75490)

      Don't trust their "equivalent to..." things. Look at the lumens [wikipedia.org] which is listed for both the incandescent bulb, and the LED bulb.

      This rule goes for buying CFLs too: They often over-estimate by about one level. (Ex: A "40-watt equivalent" is really a 25-watt. A "60-watt equivalent" is really a 40 watt. Etc.)

    • by DFJA (680282)
      Having had a similar experience I'm very tempted to report the suppliers of these products to Trading Standards (UK) as it is a clear case of mis-representing the product being sold. It's perfectly possibly to make an accurate comparison by using lumens, I can think of only one reason why suppliers don't do this - because they wish to misrepresent the product. Having said that, some suppliers do quote lumens in some cases, but it needs to be consistent.
  • Sweet (Score:5, Insightful)

    by internerdj (1319281) on Thursday January 29, 2009 @12:45PM (#26654769)
    Except I've already switched most of my house to bulbs that last longer than incandescents. Maybe the flourescents will start burning out by the time I can get some good cheap LED bulbs.
  • by Lumpy (12016) on Thursday January 29, 2009 @12:45PM (#26654771) Homepage

    Honestly we NEED a led light bulb that will DIM acceptably for people.

    most people want to be able to use dimmers and every customer I have wants to use lighting automation.

    They need to work on that second right after figuring out how to get the lumens up to that of CFL lamps.

    • by gfxguy (98788)

      I wonder if discrete stepping for dimming an LED bulb would work... you know, 5 steps: off, 1/4 of the LEDs, 1/2, 3/4, and all?

      I would imagine that you could work the logic into the bulb depending on how much juice it's getting, but then I have a pretty good imagination.

      • Re: (Score:3, Informative)

        by Sj0 (472011)

        Actually, you should be able to use a standard dimmer switch on these things. Unless someone is doing something I've never seen before, there's no logic in them, just the diode and a resistor. Maybe a capacitor if they were really ambitious.

        I'd expect control with an LED to be much better than an incandescent, because the fact that the 'light emitting' voltage stays relatively constant between the on state and off state, so you should get better effective rangability and control.

        Yes, I'm a control systems g

        • by zenyu (248067) on Thursday January 29, 2009 @01:47PM (#26655711)

          Actually, you should be able to use a standard dimmer switch on these things. Unless someone is doing something I've never seen before, there's no logic in them, just the diode and a resistor. Maybe a capacitor if they were really ambitious.

          Nope. LED fixtures on an Edison base incorporate ballasts, just like CFLs, and incandescent dimmers do not work well with any ballast. You are probably making the incorrect assumption that an incandescent dimmer just takes a sine wave with a ~ 170 V peak and outputs a sine wave with a lower peak. It would indeed be easy to create a dimmable ballast if that were the case. But instead these things just cut out portions of the wave creating all kinds of nasties on the house current. This is because it is cheaper to do, and all you need to do to dim an incandescent is to reduce it's average current consumption.

          There are a number of solutions to this problem. The one that's most likely to happen is that a new type of dimmer will be created which does something sane for ballasts like reduce the peak voltage, and labeling will be created for both such dimmers and the CFL and LED light bulbs with compatible ballasts. Another solution would be to simply put the dimming entirely within the ballast itself, then the switch would just send a message to the bulb via radio or another out-of-band channel to the bulb circuitry to dim. But while this would be more efficient, this is not going to happen in today's fragmented home automation market without a government mandate, or at least the threat of a government mandate, to standardize.

          PS There already are dimmable CFLs and CFL compatible dimmers, I have some in my house. They are not perfect, and both cost 2x as much as conventional CFLs and incandescent only dimmers; and there is no branding to tell the consumer they are compatible. This means you need to do a lot of frustrating web research before you buy the things. I also bought one bright LED Edison base lightbulb to satisfy my curiosity and it was both very expensive and non-dimmable.

          PS2 My biggest frustration with buying lighting on the web is that no one shows you a spectral diagram of the light output of the bulbs. If there are any lighting web retailers reading this, please do this and you will win some early adopter business and appear expert in the eyes of even those who don't know what they are looking at. Use, trademark and reasonably license compatibility marks and you will make a killing.

    • by gnick (1211984) on Thursday January 29, 2009 @12:52PM (#26654871) Homepage

      I've not used the commercial LED light bulbs, but standard LEDs dim just fine (at least to a point). I see no obstacle that would stop the bulbs from dimming too.

      In fact, a very quick check on the bulbs available at Amazon indicates that they do dim. Is there a dimming problem that you're aware of that's not made clear in the Amazon reviews?

    • Re: (Score:3, Interesting)

      by tlhIngan (30335)

      Honestly we NEED a led light bulb that will DIM acceptably for people.

      most people want to be able to use dimmers and every customer I have wants to use lighting automation.

      They need to work on that second right after figuring out how to get the lumens up to that of CFL lamps.

      As long as your dimmers are the electronic PWM based kind, LEDs will work with them. (CFL's have issues when they're only given part of the sinewave). If you use the crappy rheostat dimmers LEDs won't work with them.

      The only thing I que

      • Re: (Score:3, Insightful)

        by shaitand (626655)

        'If you use the crappy rheostat dimmers LEDs won't work with them'

        Why not? Adjusting resistance dims and brightens LED's just fine on a breadboard.

    • Uhh led lights are dimmable... without flickering and all that... But they are just not bright enough atm to be worth anything.

  • Clap on? (Score:5, Funny)

    by Pentomino (129125) on Thursday January 29, 2009 @12:45PM (#26654773) Homepage Journal

    I have a Clapper that I've been unable to use with CFL bulbs. I'd like to know whether these new LED lights work with the Clapper and other remote-switching appliances.

    • Re:Clap on? (Score:5, Informative)

      by ivan256 (17499) on Thursday January 29, 2009 @12:53PM (#26654887)

      They won't work with the clapper.

      Cheap automated switching devices like the clapper and some timers include the bulb as a resistance element in the switching circuit. They count on the bulb acting almost like a short when the light is off. This works with incandescent bulbs, since the resistance of the filament is very low when it is cold. CFL and LED bulbs act exactly the opposite way. They are almost an open circuit when off. With no current flow, the automated switch is unpowered.

      There are switches that will work with these types of bulbs, but they generally cost more.

  • by arugulatarsus (1167251) on Thursday January 29, 2009 @12:45PM (#26654775)
    These are going to be awesome in an office environment. Especially since the ceilings are so high and nobody likes changing the lights. But I have yet to find truly warm non-tungsten/halogen/mercury/fire/quartz/evil light for home use. I could not picture LEDs (which are basically antennas radiating a frequency that we happen to see) overtaking the other lights (heat sources that coincidentally give off visible light) in terms of color richness.
    • Re: (Score:3, Informative)

      by bishiraver (707931)

      If they can cluster LEDs in a way that simulates natural light (ie, a few at one frequency, a few at another frequency, etc) then I don't see how it's impossible... impossible for a single diode, perhaps..

    • by evanbd (210358) on Thursday January 29, 2009 @02:11PM (#26656075)

      LEDs have almost nothing to do with antennas, aside from the fact that both emit EM radiation. Specifically, there is no oscillator in the LED. The photons are a direct result of the diode band gap -- each electron-hole pair combining emits one photon with energy equal to the electron charge times the forward voltage (ie a 3V forward voltage LED emits photons with 3eV of energy, aka blue visible light). The Wikipedia page [wikipedia.org] has a fuller explanation.

      The reason LEDs produce weird light is that their spectrum is a sharp band, as opposed to the broad hump of a black body. This can be fixed (somewhat) by using a phophor to shift some of that frequency (most white LEDs), but the usual techniques for that leave a gap between the LED emission and the phosphor emission. Better, though more expensive, is combining enough different color LEDs that the narrow individual bands blend together to simulate the blackbody output. Eventually, that will get cheap enough to be common, and then you'll see LEDs in common usage as lighting.

    • Re: (Score:3, Insightful)

      by Just Some Guy (3352)

      But I have yet to find truly warm non-tungsten/halogen/mercury/fire/quartz/evil light for home use.

      I thought the same for the first week after we started migrating our home to CFLs. I've since come to understand that "warm" is a synonym for "ugly yellow".

  • by EdZ (755139) on Thursday January 29, 2009 @12:52PM (#26654863)
    And it all came about because it's hard to achieve 1000C in a shed.
  • A 15 cm silicon wafer: 15x15=225cm2
    If they fit 150000 LEDs you get 225/150000=0.0015 cm2 per led.

    Aren't they too small to be used for home lights?

    • by ericrost (1049312)

      Wafers are a disk, so pi * 7.5^2 = 176.7144375 cm^2 so you get area/150000 = 0.00117809625 cm^2/led.

      Also, 1 LED != 1 LED "lightbulb" is also != 1 LED with package size.

    • Wafers are usually circular (since they are sliced off a cylindrical ingot), so the calculation would actually be [google.com]:

      ( pi*(15cm/2)^2 )/150000 = 0.0012 = 0.12 mm^2

      Which is slightly smaller. But this means that each LED is roughly [google.com] 0.3 mm in size, which is about the size of any LED I've ever encountered.

      I presume a real lightbulb would require multiple LEDs bundled together somehow. Which is actually cool, because it would allow for more interesting bulb shapes, and should allow for dimming (by controlling how ma

  • by ChilyWily (162187) on Thursday January 29, 2009 @12:54PM (#26654905) Homepage

    So what is the energy consumed during production for one of these LED lights?
    If we're just using more energy per unit during manufacture, then what is the energy payoff balanced vs. the number of hours these will remain in service?

  • Gallium (Score:3, Interesting)

    by Hatta (162192) on Thursday January 29, 2009 @12:57PM (#26654947) Journal

    Aren't we already in short supply of gallium? Do we really want demand for this rare metal that already has so many uses? We have plenty of ways to generate light, let's use one that doesn't require one of our rarest and most useful materials.

  • Big advancement (Score:5, Interesting)

    by rift321 (1358397) on Thursday January 29, 2009 @01:03PM (#26655023) Journal

    I'm not sure everyone is completely aware of how big an advance this is. I'm going to buy Philips' stock as soon as I can. I'm sorry people have been screwed by some misleading marketing, but LEDs are the future of lighting... and the big green movement.

    And yes, they're really easy to dim, either by converting to DC and modulating current, or by using a PWM - I'm not sure which is more efficient/cheaper.

    I can't wait for CFLs to go away. Eventually you'll see commercially available, color-selectable LED bulbs.

    Anyone know if the process was patented/sold to a specific company? Pretty obvious why...

  • Ahh, 5 years... (Score:5, Insightful)

    by PowerVegetable (725053) on Thursday January 29, 2009 @01:05PM (#26655055) Homepage
    The good ole' 5-year technology promise. Close enough to be exciting and get attention, but far enough away that you'll forget about their claim before they miss their deadline.
  • Solar panels too? (Score:3, Interesting)

    by MobyDisk (75490) on Thursday January 29, 2009 @01:09PM (#26655127) Homepage

    Aren't some solar panels made with GaN as well? Will this help them too?

    • Re:Solar panels too? (Score:5, Informative)

      by giafly (926567) on Thursday January 29, 2009 @01:18PM (#26655251)

      Aren't some solar panels made with GaN as well? Will this help them too?

      Looks likely. Cambridge are researching that too, e.g. both fields are covered by the following grant application.

      The other approach to solar cells we will pursue is high-efficiency inorganic multilayer solar cells. The basic idea is that by stacking layers in the order of their bandgap, with the layer with the largest bandgap at the top, light is converted into electricity in the most efficient way. We propose to build an innovative multi-layer solar cell based on GaN/InGaN/Si. The GaN layer will absorb the UV part of the solar spectrum, the InGaN layer the blue and green parts and the Si layer the yellow, red and near-IR parts. The theoretical efficiency is above 60%. Such a cell would be too expensive for large-area applications, but would be designed to be used at the focus of mirrors that concentrate the solar light, which will make the technology competitive.

      GaN-based white lighting is extremely efficient and if used in our homes and offices it could save 15% of the electricity generated at power stations, 15% of the fuel used, and reduce carbon emissions by 15%. However for GaN-based white lighting to become widely used in homes and offices we have to increase the efficiency still further and reduce the cost. We will research various ways to increase the efficiency. To reduce the cost we will grow GaN-based LED structures on 150mm (six-inch) silicon wafers instead of the current growth on two-inch sapphire wafers. This would reduce the LED cost by a factor of ten. Cambridge will grow such LED structures and UCSB will process them into LED lamps.

      Details of Grant [epsrc.ac.uk]

  • by Twinbee (767046) on Thursday January 29, 2009 @01:22PM (#26655325) Homepage

    This is great news not just for lighting, but also potentially for ILED TVs (basically LED - the "I" stands for inorganic. It would be simpler than even OLED, and the lifetime would be amazing of course.

  • Lumens per watt is? (Score:4, Interesting)

    by AnotherBlackHat (265897) on Thursday January 29, 2009 @03:20PM (#26657091) Homepage

    Granted this is an as yet unrealized technology, but I really wonder what the lumens per watt will be.

    For reference a standard 48" T8 fluorescent is about 80 lumens per watt,
    Compact fluorescent is around 65 lumens per watt,
    and a 60w A19 bulb (the "normal" light bulb) is about 15 lumens per watt.

    Cree has some Gallium nitride LEDs that (they claim) produce a record breaking 130 lumens per watt,
    but they also have some 100 lumens per watt LEDs and they're also gallium nitride.

    Cost of production isn't totally meaningless, but over it's 20 year life, 5 watts means more than $100.

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