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Source article Here: Article

Briefly: United Airlines are giving their 11,000 pilots iPads in an effort to increase efficiency, etc. They're making manuals and other documents electronic.

As a side-benefit, they claim, there will be a big reduction in greenhouse gas emissions: 3,208 metric tons per year.

However, nowhere have I seen the emissions generated by the manafacture and distribution of 11,000 iPads taken into account.

What might the net increase or reduction in greenhouse gas emissions be? I suggest assuming an iPad is good for 3 years, but I leave that up to you.

According to Apple's Own Information an iPad2 causes 105kg of greenhouse gases from start to finish. Multiply that by 11,000 and you have 1,155 metric tons. Being their own publicised information, it could be highly idealised. Also, this doesn't include additional resources needed by the airline to roll out the devices.

Sklivvz
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puppybeard
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    The critical component missing is how much paper an aircraft hauls. Because I suspect that for a 10 pound brick the emissions of just flying it around over its lifetime may be higher than the production costs. – Daniel Iankov Aug 25 '11 at 11:14
  • This change is being made because it will reduce fuel consumption and give other benefits. That it reduces its "Carbon Footprint" is the green spin. If it increased carbon footprint but reduced operating costs United would still do it they would just do it quietly. – Chad Aug 25 '11 at 20:45
  • Chad, I think you're right. That's why I thought I'd see what people here thought. – puppybeard Aug 26 '11 at 08:54
  • @Puppybeard i think that the carbon footprint is a scam to make money selling carboncredits. But I am not allowed to ask that here. – Chad Aug 26 '11 at 14:51
  • Chad, the way I understand it, carbon footprint is just another name for "total greenhouse emissions". I don't see how that could be a scam. As for carbon credits, I think their benefit is exagerrated, and they're an excuse for companies to pretend to be environmentally friendly without making any systematic changes. Planting trees is good and all, but things don't cancel out magically. – puppybeard Aug 27 '11 at 08:46

1 Answers1

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The iPad weighs about a kilo, and replaces 17 kilos of paper. Hauling around a kilo of payload takes about half a kilo of fuel (mostly spent in achieving altitude). So with 1000 flights per year (this differs per airline, short hop planes fly more), each iPad will save about 8 tons of fuel annually, or about 20 tons of CO2. That's already two orders of magnitude better than the 105kg from production in the first year of use.

Additional environmental benefits come from the fact that a lot of the paperwork changes over time: a large part is maps and regulations of all airports, and these do change over time. (e.g. warnings about buildings near the flightpath). Producing and distributing several kilos of updated books takes far more resources than a download.

[update] United is actually a lot less optimistic: "Saving 326,000 gallons of jet fuel a year reduces greenhouse gas emissions by 3,208 metric tons." That's less than 1/3rd of a ton per iPad. And to a degree, that makes sense: I had silently assumed that each iPad flew a thousand flights a year, because every plane did. But United has ~6200 pilots and ~460 planes. Clearly each pilot gets its own iPad, not each plane. And that probably also means there will be two iPads per plane.

MSalters
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    And change a lot those books do... While some of the charts are on a 6 month cycle, the biggest set of books (the approach plates) are replaced every 28 days! As a private pilot, I go through what seems like a mountain of them just having them for the tri-state area that I live in. Commercial pilots that may need the entire set are throwing away (recycling hopefully) a whole bookshelf worth that often! Side note, I tried electronic charts, but went back to paper as it's more reliable and is actually cheaper overall for me... – Brian Knoblauch Aug 25 '11 at 13:18
  • From [Apple's](http://www.apple.com/ipad/specs/) page, the iPad 2 will weigh about 600g, or HALF a kilo. – fred Aug 25 '11 at 13:22
  • Can you please quote where on the wiki page you got the figure of "Hauling around a kilo of payload takes about half a kilo of fuel (mostly spent in achieving altitude)." – Scott Chamberlain Aug 26 '11 at 19:50
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    Two iPads a plane sounds like a good idea to begin with -- single points of failure being a bad idea, and all... – Shadur Aug 27 '11 at 12:55
  • *"8 tons of fuel annually, or about 20 tons of CO2"* ??? – vartec Aug 27 '11 at 21:02
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    @fred: 1kg = 1000g, not 1200g ;-P – vartec Aug 27 '11 at 21:06
  • @vartec: CO2 has a molecular weight of 44, only 12 of which is the carbon atom. But jet fuel isn't all carbon; it also contains hydrogen and other atoms. – MSalters Aug 28 '11 at 22:33
  • @Scott Chamberlain: from the payload capacity and the fuel capacity; deduct some margin for the fuel reserves. – MSalters Aug 28 '11 at 22:34
  • @MSalters, You can not do that, as you did not account for the accuracy of those numbers, the error bounds can easily be more than +/- 1/2 kg/lb. "On the 777 you can add or subtract 100lbs of thrust without the gauges showing any change [1]". This is a PR ploy by united, the way they figured this number is like this "Every everyone in the state of new york drive 0.1 MPH slower the state would save over 100,000 gal. of fule per year"[1], now that statement could be true, but is is possible for you to consistently drive your car .1 MPH slower? [1]Direct quote from a captain of a 777 for United. – Scott Chamberlain Aug 29 '11 at 14:45
  • The united captain who gave me that quote flies a [777-200LR](http://en.wikipedia.org/wiki/Boeing_777#777-200LR) with a total thrust of 90,000 per engine. On another note to re-enforce how little weight savings there will be, the 777-200LR weighs 138,100. removing 16 Kilos would change to total weight by 0.0094%. – Scott Chamberlain Aug 29 '11 at 14:53
  • Also, going back to the fact that they can not detect a change of 100lbf, that is 444.8N of Thrust, So you have a bare minimum +/- of 444.8N error to measure a 16 Kg change of mass, well within the error bounds. – Scott Chamberlain Aug 29 '11 at 14:56
  • @Scott: I'm an engineer, I know how to estimate these things. Error bounds in the iPad weight? They're drowned by the error bounds on the weight of the paper (~30 times larger). Cannot detect 100lbs trust change with one measurement? That's rounding error and cancels rapidly with multiple measurements. As for the small % saving, well, airlines _do_ emit a lot of greenhouse gases. 16 kg is approx. 1/6th of a passenger on every plane, every flight. That's obviously more than 0.0094%. – MSalters Aug 29 '11 at 15:15
  • What I am saying in real world conditions a 16kg change in the mass of the airplanes is swallowed by the error bounds of the fuel consumption of the engines. I agree that the useage could be .5 (kg fuel / kg payload), but the realworld case is .5 (kg fuel / kg payload) +/- X, Where X is a lot bigger than .5. You are measuring feathers with truck scales. – Scott Chamberlain Aug 29 '11 at 15:30
  • @Scott: Wrong; it's +/- (X/sqrt(N)). You've got more than one measurement. Given enough feathers, a truck scale _does_ work. – MSalters Aug 29 '11 at 18:13
  • @MSalters let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/1222/discussion-between-scott-chamberlain-and-msalters) – Scott Chamberlain Aug 29 '11 at 18:41