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They even referred to the carbon emissions of e-readers vs. physical books and quoted a break-even point of 40-50 books. I believe they used this figure is taken from Goleman and Norris' life cycle analysis, and it is much higher from the break even point we found when we looked into it, which is 17.4 books.
Also, if I'm right and their figure is based on Goleman and Norris' work, then I think there's a little mistake here - according to Goleman and Norris "when it comes to global warming, though, it’s 100 books". The figure of 40-50 books mentioned in their analysis with regards to "fossil fuels, water use and mineral consumption." The analysis of Goleman and Norris is available at http://www.nytimes.com/interactive/2010/04/04/opinion/04opchart.html
As I mentioned, our figure is 17.4 books and is based on the following calculations (you can read more about it on our analysis of the iPad's environmental report):
For this comparison, I'll use the figure of 7.46 kg of CO2 to represent the lifecycle carbon emissions of an average book. This figure was presented on the Cleantech report (The Environmental Impact of Amazon's Kindle) and according to the report based on three independent studies that used life cycle analysis calculators to assess the impact of raw materials (I know it's much higher from the figure of 4.01 kg presented on the 2007 'Environmental Trends and Climate Impacts: Findings from the U.S. Book Industry' report, but I believe it helps to make the comparison more balanced).
Now, according to Apple's lifecycle emissions of an iPad (Wifi and 3G model), its carbon footprint is 130kg CO2e. So, comparing between the two gives us the following equation: 1 iPad = 17.4 physical books.
In any case, we definitely agree with the bottom line of Goleman and Norris that is also quoted here - walking to the library is still the most eco-friendly way to read.
Yours,
Raz @ Eco-Libris
Eco-Libris: Promoting Sustainable Reading!
