back to article Powering your iPad costs $1.36 per year

If you charge your fully depleted iPad every other day, it'll cost you a buck thirty-six per year, according to a just-released study by the Electric Power Research Institute (EPRI) of Palo Alto, California. "At less than a penny per charge these findings bring new meaning to the adage, 'A penny for your thoughts'," said the …


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  1. Richard Cartledge

    Wow, iPad would be ~£3 at UK kWh prices.

    1. Anonymous Coward
      Anonymous Coward

      Cheap.. In the USA

      Cheap.. In the USA

      Here in the UK it would be a mind blowing £6.80

      Show how much we get ripped off.

      1. Anonymous Coward
        Anonymous Coward

        We try not to rule the energy producing Nation's, though that may not be true.

      2. brone

        I don't think this follows from the stated figures!

        12KWh * £0.12354 * 1.05 = £1.56. If you'd like the standing charge included, for me that adds £0.015/KWh, making it more like 12KWh * £0.139 * 1.05 = £1.75.

        You'd be paying something like £0.54/KWh to make it £6.80! - perhaps it costs that much in the Shetland Islands, but this is out of line for most of the UK. You can pay more than £0.12354/KWh, but not THAT much more. I'd advise shopping around.

      3. Naughtyhorse

        shows how much the merkins dont give a fuck about the state of the planet

        there fixed it for you

  2. benzaholic

    comparing to a 60W CFL?

    I'm not sure I've even seen a 60 Watt compact fluorescent light.

    The ones I use that put out about as much light as 60W incandescents are rated at something like 13 or 17 Watts.

    1. Anonymous Coward

      Re: comparing to a 60W CFL?

      I'd expect such failures from most company "mathematicians". :(

    2. stanimir

      Re: comparing to a 60W CFL?

      60W CWL?

      I was WTF!?!

      I the highest available to buy is usually 23W, 60W "compact" can potentially overheat.

    3. Tom 7

      Re: comparing to a 60W CFL?

      The 60W CFL is really the 7 or 8 W model with the lifespan of a mayfly and the receipt written in invisible ink so you cant even waste time going to the shop to get your money back.

      1. Lunatik

        Re: comparing to a 60W CFL?

        "The 60W CFL is really the 7 or 8 W model with the lifespan of a mayfly and the receipt written in invisible ink so you cant even waste time going to the shop to get your money back."


        I've still got some of the original CFLs bought for my first flat in 1997. I've also bought ones that failed within 2 weeks, just like - hey! - incandescents.

        In a temperate (alright, cold) country like the UK I'm agnostic about the benefits of CFLs, but I don't like to see the usual tripe peddled about them being whale killing, ozone zapping eco nightmares. In warm climes they make a much better case for themselves.

  3. Paul Crawford Silver badge

    But what is the cost of running (rechargeable) battery powered sex toys we ask?

    1. Yet Another Anonymous coward Silver badge

      She normally just makes me a sandwich

    2. Anonymous Coward


      I charge up my toys using a solar thingy!!

  4. Azzy

    I'm not sure I trust a research group...

    that doesn't understand the concept of significant figures.

    Also, most certainly they referred to the 60w equivalent CFL - otherwise, they might as well have said 60w light bulb....

  5. David Given


    The iPad has a 25 Wh battery, which is 25*60*60 = 90kJ. Assuming we charge it from flat every two days, that's 90kJ * 180 = 16.2 MJ. Assume charging efficiency of (wild guess here) 10:1, that's 160 MJ over a year.

    Electricity cost is about 10p per kWh, so that's 10 / 1000*60*60 = ~3x10^6 pence per joule.

    So over the year, our 160MJ is costing roughly (*very* roughly!) 480 pence.

    Given how many numbers I made up, the fact it comes out at the same order of magnitude as the poster does suggest that their figures are at least plausible.

    1. Ole Juul


      The energy cost of replacing the batteries when they eventually wear out needs to be included in the "energy consumption". After all, people aren't running their their iPads off the charger.

      Probably though, the attention span of iPad consumers is shorter than the lifetime of the batteries. In other words even discussing power consumption through the charger is irrelevant outside of the original engineering concerns.

      1. Haku

        Re: Meaningless

        There is a lot of evidence to suggest that many people will not get to the stage of needing a replacement battery for their portable computing device as they have a contract (in the case of a phone) which entitles them to upgrades, or they buy the newest version of the gadget when it's released every 1-2 years anyway.

        So really shouldn't the whole cost of the device be included into the study?

        1. Ole Juul

          Re: Meaningless

          So really shouldn't the whole cost of the device be included into the study?


          Unless it was actually a psychological study - and they're testing us to see if they can get away with saying "powering your iPad costs $1.36 per year".

  6. Anonymous Coward
    Anonymous Coward


    > compact-fluorescent lightbulb eats up just a bit more power – about 14kWh – and costs $1.61 annually. But is that bulb burning 24/7?

    Yes they are left on 24/7. They take so long to actually light up that I leave the ones lighting up stairways on 24/7.

    1. E Haines

      Re: CFL

      You must have crap ones then; the ones I've got light up to full brightness instantly.

      1. Haku

        Re: CFL

        I've been experimenting with LED lighting, in this case those 5 meter 300x 5050 sized LED strips that are great for whole room lighting once installed right (pointing at the walls/ceiling instead of directly down works well).

        I found that the normal white LEDs are too 'cold' and blue in colour whilst the 'warm white' ones are almost too yellow, but if you use an equal mix of the two types you get a really nice daylight-ish white. Throw in some dimming circuitry and you can fade between the two types of white to get the 'perfect' blend.

        1. stanimir

          Re: CFL

          LED are brutally expensive, though

  7. Richard Scratcher

    Not so expensive!

    My iPad is topped up by a charger linked to a bank of solar cells. So converting to UK prices I would guestimate that I spend a good 2.5% less than the figures suggested by EPRI (assuming a good summer).

    1. Anonymous Coward
      Anonymous Coward

      Re: Not so expensive!

      My iPad is powered by biogas given off by smug ecotypes who would buy an iPad, and then think "I know what will make this tech device efficient - I'll use expensive solar panels to charge it, panels that I'll mostly keep idle so as to make the process even less efficient".

      The environmental cost of the solar panels will massively outweigh the 'savings' from not plugging your iPad into the mains.

  8. Anonymous Coward
    Anonymous Coward

    I'm scared to see what my pair of Phenom 2's and pair of 4 series Nvidia GPU's draw from the grid.

    1. Luke McCarthy

      I'm sure it's a Phenom-enal amount.

  9. Anonymous Coward
    Anonymous Coward

    No Reg units of measurement?

    This "Watt" business really is quite ridiculous. I thought we had settled on hamsters as a proper measurement of energy.

    Tut, tut.

    1. Flocke Kroes Silver badge

      Plenty of loony units of measuments measurements

      A Watt is a unit of power (1 Joule per second). The SI unit of energy is the Joule. Take your pick from:

      kilo Watt hours (Energy supplied by an electricity company): 1kWh = 3.6MJ

      British thermal unit (Energy supplied by a gas company): 1BTU = 1.055kJ

      Foot pound force (A unit of energy - honest): 1ft·lbf = 1.356J

      Calorie (Energy spent while exercising): 1cal = 4.2J

      Calorie (Energy content of food): 1Cal = 4.2kJ

      Electron Volts (Energy per particle in a particle accelerator): 1eV = 1.602E-19J

      Litre (1/1000 of a cubic metre) of petrol: 34.2MJ

      Kiloton (Energy in 1 ton of TNT): 1kt = 4.184GJ

      The units of power are just as bad. The most common is:

      1Windturbine = electrical energy used by 10billion homes with gas hot water, cooking and heating, petrol driven transport, food from high energy content fertilisers, candles for lighting and the average number of gadgets for a family living in a remote corner of a rain forest.

      1. Anonymous Coward
        Anonymous Coward

        "Calorie (Energy content of food): 1Cal = 4.2kJ"

        Tut tut. I'm pretty sure you mean "kcal" (kilocalorie). You know, a bit like kilometers and meters.

      2. John Robson Silver badge

        Re: Plenty of loony units of measuments measurements

        The scientist was called Joule, the unit is a joule, which is abbreviated to J

  10. Katie Saucey

    Comparing computer use to light bulbs..

    OK fine, to justify my tablet/phone/desktop/LCD TV etc. usage, I'll just smash a few more 400W street lights on my walk back from the bar.

  11. Andus McCoatover

    In other unrelated news...

    I've discovered that the simplest way to reformat the flash on one's latest fondleslab is to simply leave it charging (there's my $1.36-worth) on top of the microwave oven whilst girlie warms up a kebab.

  12. Anonymous Coward
    Anonymous Coward

    Plasma power consumtion

    Is likely flawed, as whilst a TFT based telly uses a backlight that draws a constant power regardless of picture content, on a plasma there is no backlight, the power consumption is based almost entirely on what's being displayed. A dark scene will draw very little, a light scene lots, but unless you only ever watch your skiing holiday movies on your plasma, the liklihood is the AVERAGE power consumption will be close to that of a TFT (LCD/LED)

    At the end of the day, there is little difference between modern plasmas and TFTs, unless you have an agenda, in which case, you can manipulate tests to make TFT seem more energy efficient.

  13. biz


    Why not publish these costs in English money too. Then we might have a better idea.

    1. Anonymous Coward
      Anonymous Coward

      Re: Costs

      Maybe we should - but is it really necessary? Just about everyone outside the US has a sense of how much a dollar is worth, in relation to their own currency.

      1. Jeebus

        Re: Costs

        You mean it is just laziness, thanks for clearing that up.

      2. Confuciousmobil

        Re: Costs

        A dollar is worth about 1 pence, right?

      3. You have not yet created a handle

        Re: Costs

        Because you a UK based site?

      4. Anonymous Coward

        Re: Costs

        He probably thought this was a British website. It's an easy mistake to make, with that TLD. You really should fix it. .us domains are available for a few pounds dollars.

  14. Panimu

    Very wanky article. Poor show Reg.

  15. daveeff

    I may hang my fondle slab in the stair well, it gives out about as much light as my low energy bulb and apparently costs less to run.

  16. sebacoustic

    i wonder... many tablets or phones one could power with the energy equivalent to the air conditioning and commuting caused by this institute in Tennessee?

    Just coming back from a trip to the southern united states, the vast amount of energy consumed there is still foremost in my mind.

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