iPad? How bad?

Update: So it looks like my estimates for the carbon dioxide emissions were way off.  I guess iPad’s components must be particularly carbon-unfriendly per unit mass; if I had to speculate, it’s due to a higher component weight to frame weight than on the computers considered here.  Updated results at the end of this post; you can follow along using the original text, substituting in the new values for manufacturing.  It looks like my estimates for power adapter efficiency and power consumption are pretty much spot on, though.

Jorge Aranda tells me his brother is considering one of those newfangled iPads to reduce his environmental footprint:

His reasoning is that it will help him pay for “content” without damaging the Earth –specifically, he’s talking about reading the newspaper, magazines, and e-books in the iPad, instead of buying them in paper version.

I suspected, and told him, that on the whole this would probably mean an *increase* in environmental damage, rather than a decrease. He’s not convinced.

Jorge then adds the question that prompted the creation of this blog: “Who is right?”

So will buying an iPad to replace print materials reduce carbon emissions or just result in more iWaste?

Waste attributable to the iPad

To calculate the net change in CO₂ by using an iPad instead of using paper, regardless of how often the iPad is used for reading, the entire manufacturing waste should be taken into account.  Why?  Simple cost-benefit analysis: compare the status quo CO₂ emissions to the alternative. In most cases, the iPad will be an addition to one’s computing family. But if one buys an iPad in lieu of an iPod Touch, iPhone, or similar device, one could instead look at the difference in manufacturing environmental impact.  Here, we’ll look at the first case, the worst-case scenario; the entire CO₂ cost of manufacturing the iPad needs to be considered.


We’ll simplify the results of Williams ’04, as we did in To Print or Not to Print?: manufacturing a computer results in 10 times its weight of CO₂ being produced.  The iPad weighs 0.73 kg, so we end up with 7.3 kg of CO₂ produced as a result of manufacturing.  We’ll ignore shipping and packaging, although we should note that toting around an iPad is more energy intensive than carrying a few sheets of paper.  Unless toting a heavy book around is the alternative, once the iPad is purchased, a rise in emissions due to transportation will result.


We will assume the average reading rate per page is 5 pages per minute.  This rate includes pages that would have been ignored  if used in its printed form (e.g., the sports section in my copy of The Globe and Mail).  We will assume the supplied USB power adapter is used and that it is 80% efficient.


The iPad runs for 10 hours on a 25 Wh battery while surfing the web with Wi-fi.  Since the MacBook Air really does get the advertised battery life, I will assume that this isn’t just 10 marketing hours.  This means the iPad uses a meagre 2.5W!  We assumed a reading time of 5 minutes per page, so that means reading a page requires 0.26 Wh, after factoring in losses from the USB power adapter.  Using numbers for power generation in Ontario, that works out to 0.12 g of CO₂ per page.  The results of the calculations in To Print or Not to Print? give us a figure of 2 g of CO₂ per side of printed text on recycled paper with recycled toner.  From here, all we need to do is solve for x:  2x = 7300 + 0.12x.  Our break-even point, x, is therefore about 3883.  To be safe, we’ll say 4000 pages (or, really, sides).

The Verdict

At an average reading rate of 5 pages per minute, if owning an iPad saves 4000 sides of paper from use, it’ll have resulted in a net reduction of CO₂ (remember, there are other unwanted byproducts we didn’t consider).  At 5 minutes per page, that’s 333 hours of reading.  If one owns an iPad for 24 months, that’s about half an hour of reading each day.  Will the iPad’s battery hold up to that?  Well, considering it runs for about 10 hours on a charge, that’s about 33 discharge cycles.  If the battery is the same as the new type used in the MacBook Airs and MacBook Pros, that’s only a tiny fraction of Apple’s estimate of a lifespan of 1000 charges. A faster reader is a more environmentally-friendly reader on an iPad! Reading more dead tree media quickly makes you more like a beaver in the print world.

It impresses me that it doesn’t take much reading (in my books, anyway) for an iPad to pull ahead of print, even after accounting for its manufacturing.  Me? I’ll stick to my iPod Touch and laptop until the iPad can serve all my computing needs which, considering my primary computer is a MacBook Air, probably won’t take much beyond letting me run my own apps. But to return to the original question: Jorge, the iPad? Not bad.

Update: After crunching the new numbers from Marek, it looks like one needs to read 35000 pages to break even.  Somewhat fortunately, for someone who otherwise would read a newspaper or magazine, this includes the pages that one skips over.  However, that’s still a very large amount of reading.  I will have to retract that “not bad” verdict — at least from an emissions perspective.

18 Replies to “iPad? How bad?”

  1. So environmentally it isn’t that bad even though you could just reuse devices you already own to read things.

    But on the civil rights front it is atrocious, you have a locked down device that has literally censored software and content. The device reeks of prudishness. Also this device can’t be used as an educational device because Steve Jobs in his wisdom has decided that programmers are second class citizen. So have fun installing something like MIT’s scratch on there for the kids to learn programming.

  2. Cute and all as a start but I think you need to really compare to whole life cycle (production, usage, disposal) of an eReader to the life cycle of a normal book that can actually be shared and be made of recycled paper.

    Not mentioning how people use the device and will need to recharge more, will force small time buyers to get a device for locked titles in the system that can’t be bough anywhere else. Shipping cost, servers running the eBook infrastructure, the whole ecosystem basically!

    1. Alex, you’re right — I didn’t take into account the disposal of an iPad (I wasn’t looking at any other readers), but you can tack on an extra 30% of pages you have to read. I did take into account the full life cycle cost of recycled paper (as opposed to what I had done in my less-favourable-to-paper analysis in To Print or Not to Print) and the energy required to recharge (0.26 Wh per page), though. Shipping an iPad results in negligible added CO2 output when amortized over the number of pages suggested above. I suppose you also have a point with the small time buyers getting a device for exclusive titles, but as more content (including media other than print) becomes available electronically, this becomes less of an issue.

      However, you make an excellent point and the most important missing quantity in the calculations above: powering the servers for electronic content. At first, I thought you got me — I thought paper would again come out ahead. However, upon further thought, factoring this in *might* actually favour electronic content. We’ll assume that the content companies are smart and are using virtualized or shared web servers; this is usually cheaper (unless you have computing needs the size of Amazon or Google). This means that we can pretty much ignore the idle energy consumption of the servers. Because virtualized servers tend to run at around 40% utilization (too much deviation from this means capacity probably hasn’t been well-provisioned), we can tack a 60% energy “surcharge” onto the download of a book. A slightly higher amount if you want to factor in the network equipment of the Internet, too. But consider that a server can probably handle at least a hundred requests simultaneously, a text download might consume 3000W end-to-end (we’ll factor in all the air con and back-up supply energy losses) for a tenth of a second.

      We can then look at how CO2 production changes for people obtaining content in print form. If you go to, say, Amazon, and order a book, there’s also a lot going on to get your book to you. If you go to a (large) book store, there is a lot of computing going on, but behind your back. Delivery of magazines and newspapers to your door also requires energy. Those vehicles delivering paper to your door stop traffic – slowing down other cars, etc.

  3. This is amazing! I am trying to do something similar with reusable travel mugs vs disposable cups.

    Something Apple does well is offer take back/recycling programs for most of their products. I think it’s something you have to take into consideration either when calculating manufacturing costs (although this might be negated by the transportation required for the take backs) or as a separate factor. I have written a bit more on considerations for purchasing computers sustainably in general here.

  4. What about the fact that it cant even run flash? that its going to be so limited to what apple allow you to have on it, and with current predictions, in a month or 2 you can get an HP version of it with windows 7 running and 2 degital cameras attached for a tiny more money? The brand is lovely but i think there are much better options available out there.

  5. The problem with the iPad is that it is part of an entire system of predetermined obsolescence. Essentially, we jump to buy the new products that apple comes out with while our old products are gradually being phased out. If you want proof for this, try to find a case for the first generation nano on the apple website. Try to buy any accessories for any of their products that are two generations or more old. Having trouble right? Apple phases out these accessories as a counter-incentive to buy their newest products. As apple comes out with these new products we trash our old ones they end up in third world countries to be disposed of as our countries continue to export our environmental externalities. And apple is not alone, other corporations that make cheap and disposable products that have a predetermined end of life (e.g. wal mart making cheap toasters and microwaves) are also involved in this system. So the iPad may alone be better than using paper but lets try to avoid buying superfluous electronic items because they are part of broader social and environmental issues.

  6. Of course you can come to weforest.com and buy a tree to offset your iPad’s CO2 impact.

    I am wondering though how goods books, if they are kept for a long time, are at sequestering carbon.

    Some of our books have been in our family for generations if they continue to sit on the shelf then the carbon in them stays out of the atmosphere.

    On the other hand if an iPad ends up in Landfill the plastic probably holds onto its carbon for a very long time…

  7. You are of course missing the energy required to transfer the content to the iPad. The amount of data that gets shuttled around the Internet is non-negligible. Passing through many routers and switches which run in data centers with massive cooling, plus one wireless hub at your home, this sure will worsen your total energy consumption calculation, possibly to a point where carbon break-even will never be reached.

    I once read somewhere that the Internet (including end-user devices) now amounts to more than 10% of global electricity use.

    1. Thanks for commenting, Matthias! Yes, I did miss the energy required to transfer content as pointed out by Alex above. However, regardless of whether the 10% figure is true (it doesn’t seem outlandish), I think we need to consider what the energy used by alternatives are. For example, LCD monitors are not low energy consumers by any means, but the CRTs they replaced at the time consumed about three times more. This does not factor in the differences in hazardous material nor the fact that LCDs are now larger, which reduces their energy advantage over CRTs. Something that is certainly worth mentioning, however, is the Jevons paradox (increases in efficiency lead to increases in consumption rate) and the effects of making accessing content easier.

  8. Any research into the lifecycle cost of books has to look primarily at the cost of getting them to your door – at the very least it’s the same carbon impact as production and can be much, much higher. Whether you drive to the store, walk to the library, or order from amazon is the single greatest determinant on the carbon impact of conventional books.

    1. Thanks, Ben — just to clarify, I ignored the lifecycle cost of transporting the iPad, not paper. However, if you have a source that gives numbers on the carbon impact of shipping books (or paper) to your door, it’d be great if you could send me a link. Right now, my estimates are very Canada-centric and err, I think, on the side of overestimating the carbon impact of paper.

  9. Perhaps we should think more about whether iPads OR print material use are sustainable. Just because one is better than the other doesn’t mean either are “OK”. I would suggest Jorge’s brother evaluate his entire environmental footprint and determine whether the addition of an iPad (or magazine subscription) would push him above the threshold for individual sustainable greenhouse gas emissions (which is about 1.5tonnes per person per year, I think – can’t find the reference right now but the figures are in the film “Age of Stupid”).

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