Black Google would save 750 Megawatt-hours a year

June 20, 2007

My colleague Jyothish sent me this info:

An all white web page uses about 74 watts to display, while an all black page uses only 59 watts.”

Google, which has a white background and gets about “200 million queries a day” could reduce global energy use by 750 Megawatt-hours a year by simply changing the color of its homepage to black.

For more, visit Blackle.


30 Responses to “Black Google would save 750 Megawatt-hours a year”

  1. NAREN Says:

    Charity Begins at home….. So, belluranna when will this blog becomes Blacky……..???? is makeover of this blog necessary.. Well wat does readers say..?????

  2. Astounding discovery. Pls dont tell me next year that i have developed a squint which can not be rectified due to peering at the black god for years!!!

  3. Picasso Says:

    Somebody didn’t think too hard about this one.
    Most everybody these days are using LCD screens instead of the big clunky CRT monitors. The backlight design of an LCD means that it’s actually using no energy to display a white pixel, and a small voltage is applied to each of three sub-pixels to display a black pixel. Might have been a good idea ten years ago, but not anymore.

  4. rk Says:

    blackle may save energy, but from a user friendly stand point websites with black backgrounds and white text are very hard on the eyes. For those with eye problems blackle may not be the best fit. (re: mohan’s comment)

    lol! 😀
    don’t worry, coz blackle will save energy only if you’re using a cathode-ray display… it makes no difference on an LCD.

  5. Shanthi Manian Says:

    On a mac, you can invert the colors of your screen by pressing Cmd+Option+Control+8. One way for Mac users to save energy.

  6. Dan Says:

    significant energy savings will only be for CRT monitors which are falling out of favor in the pc market. few current-generation LCD monitors support localized dimming so they use virtually the same amount of power regardless of the color displayed. still though, it’s nice to see google provide a simple change to their service that helps save energy.

  7. sastry Says:

    The amount of computing power used to create these black pages, and even discuss them, likely negates any supposed savings. Please Bellur, for the sake of readability, don’t darken your highly inspiring blog.

  8. paolo Says:

    Only if you’re using a cathode-ray display… it makes no difference on an LCD.

  9. ericsoco Says:

    black pixels actually take more energy to display on LCD screens than white pixels do.
    with no electricity passing through the polarized filters, a subpixel will allow all the backlight to shine through to the front of the screen. blacking out a subpixel requires an additional charge.
    the third and fourth paragraphs in this wikipedia entry, focused on ‘twisted nematic devices’, the most common type of LCD display, explain this in more detail.
    thanks for the effort tho…

  10. jaime Says:

    Looks like many have jumped on the “Blackle Bash” bangwagon….and I agree that many of the arguments, with respect to CTR v LCD monitors etc, have been valid.
    However its’t it worth considering the bigger picture. Of course sites such as blackle do not result in huge savings to the environment, on the contrary, the savings are very small. However isn’t that besides the point. Surely the environmental awarness created far more valuable..Take the Live8 concerts a couple of years ago as an example. These concerts were not staged to raise money and immediately fix world poverty. They were staged to create ‘awareness’. Now, as a result of the concerts, political leaders have been forced by their constituents to act.
    So before we jump on the “blackle bash” bandwagon I think we should all take a step back and appreciate that we are all fighting the same battle – saving our environment. Sites like blackle are only a drop in the ocean, but at least they are fostering important environmental awareness!

  11. lee Says:

    To put this in further context, the total theoretical savings from this are equivalent to about 1.5 seconds of world electricity consumption, or around 1/7 the output of a utility-scale wind turbine with a blade length of 71 meters.
    Drop in the bucket, to say the least, and it’s never going to happen in any case.

  12. pArijAta Says:

    I received this information via email a few days ago, and this blackle thingy was quite hard on the eyes. And thanks to this post and the comments that followed, I don’t feel guilty about not using it!

  13. Praveen GK Says:

    If google changes its page to black, almost all will neglect the search engine. 🙂

  14. Cuckoo Says:

    Oh good that many people have views similar to mine. I can not see myself using a black background.

    They are very hard on eyes and I am very much worried about my future ! 😉

    And please, you also don’t change your blog to black if you still want me to come here. (That was a polite warning !) 😛

  15. Hi RK,

    Thanks for pointing that out. Good point.



  16. rajesh Says:

    wow.. don’t people at least skim the existing comments before posting to avoid repeating the same point? If we all did that, the energy saved from less time spent at the computer might be significant.

  17. dave Says:

    Actually Blackle is owned by Heap Media. It has NOTHING to do with google! It is a sham.
    As someone else already pointed out the energy saved by saved by a CRT monitor is very little, and that is off set by a LCD which needs more power to re-create black since a LCD display does not naturally do black colors.

  18. sriniu Says:

    I think there might be some justification in the logic behind making google all black. But lets not divert our attention from things which can really make a change (like switching off lights when we do not need it, using less of plastics and so forth) unlike the small benefit which can come from making google site black.
    The blackle site however looks like a clever attempt to gather business in the web search space, capitalizing on people’s gullibility.

  19. ram Says:

    Someone above suggested we worry about what type of power we use instead of how much. I just wanted to point out that the focus should of course be first on how much power we use. End-use energy efficiency is the best way to take a big bite out of the energy problem. Any inefficiencies in transmitting source power to power we use at home are multiplied up the distribution chain. For example, if we save 1 Watt of power at home, that might translate into savings of 3 Watts of source power due to inefficiencies. Not only are we not needing to create this power (through a dirty or clean method), but we no longer have to pay for it either, so we actually save money. Cleaner and cheaper – that’s why we should all be worrying about energy efficiency first!

  20. mark Says:

    A few other points that have come up.
    Generally, yes, CRT use is declining, but they are still in widespread use, particularly in China (50% of all monitors) and Latin America (75% of all monitors)
    Also, plasma and OLED use is rising. These follow the same idea, white is expensive.
    Finally, it’s not just Google. If every high volume site did this I’m sure is would really add up; 1000 comparable sites and we have 75 million dollars saved in electricity. and you get double points for converted sites in China, and triple points for converting sites in Latin America.

  21. sudhi Says:

    interesting concept, but their numbers aren’t valid at all.

    first off, if we’re talking about CRTs, theyre powered by electron cannons firing at a phosphorus sheet. the power taken is a function of the efficiency of the electron gun. different monitors consume different amounts of power.

    in an LCD, on the other hand, i dont think there is a power difference at all.

    while this is well-intentioned, it is inherently misleading for them to post 4k megawatts saved so far, and such claims. what we need to be doing is worrying about where our power comes from, not how much we consume.

    Incidentally, if such a shift of color scheme would make any kind of significant difference, they should be pushing to have people switch their entire windows themes to the way i used to have my boxes set up. black on black, with grey or white text. then every application would consume less power at all times.

  22. robert Says:

    If you are on a Mac (OS X) you can use a powersaving (usually) shortcut key combination which displayes in reverse video.

    CMD + CTRL + Option + 8

  23. aditya Says:

    Sorry to add more skepticism, but a white on black design is well understood to be harder and slower to read. I expect this means Web site users on a site using such a “low energy” design would end up needing to spend more time at the site reading the text. In another treegugger thread on black google it’s noted that in one study 12 of 15 subjects took longer to read white on black text.
    The math incidentally in that other thread seems very wrong. I calculate from their assumptions a potential $208,000.00 savings on 2.098 megawatt hours, not $75,000.00 on 750 megatwatt hours.

  24. O_Crítico Says:

    This is very inacurate, i’ll explain:

    In CRT’s you Might have a quite good power reduction, because in a CRT the colors are generated trough a cannon that works at an high voltage.

    Now since “black” means “no bombarding phosforus” at all, it also means that i wont need energy to genrate a 100% black page. (or i would need less energy) in the other hand, a white page would require much more energy.
    Now here’s the twist, CRT’s are disapearing, i’m one of the few who has a professional 21 inch CRT.
    LCD’s on the other hand work the other way arround, they are white (bright back light) the only thing that keeps them black is the big transistors array that makes the color when polarizes the liquid cristals hence de name LCD…,
    So to make black you would have to instigate energy to those transistors so it would be more expensive to have a black page than a white page (by 4 or 5 watts :p)

    it’s not by any change that those old gameboys have a contrast dial and you were able to save energy by keeping the contrast to a minimum

    Ps i’m sorry about my English

  25. bachodi Says:

    Its a pain sir , to read white letters in black screen.
    If all employees of Major SW companies in india switch off moitors when unused , it will save more energy than what blackle can save.

  26. 1David Says:

    Black Google
    you can even customize the logo too

  27. this one has better viewing results in terms of colors

  28. Greenle is more cool.

    And the energy savings are not true with a black background (LCD screens may use MORE energy to show dark colors)

  29. Jason Says:

    I use which is similar to greenle but it saves more energy. It is hosted on a server that is powered by wind and sun energy. Black search engines do not save energy as they claim and also my eyes twitch after seeing that black background.

  30. martha Says:

    I prefer Blackoogle..the same but with more functionalities: – US – UK



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