What has a lower carbon footprint — buying a book from a local store or ordering it online?  What about buying your books via a Kindle or other e-reader?

Amazon, the leading online seller of books, has been very coy about revealing their carbon footprint (although they point out lots of things they do to make their deliveries more environmentally friendly).  However, the findings from a case study of Buy.com may provide insights into the eco-friendliness of e-commerce more broadly.  The study finds — perhaps surprisingly — that shopping online is often more energy efficient than shopping locally.

On average, shopping online was 30% more energy efficient than shopping locally, but there was a large amount of uncertainty and variability in many of the numbers that went into that analysis.  By varying several of the largest contributing factors, shopping locally can easily end up being the greener option.  In particular:

• Shipping express or otherwise getting an item via air delivery increases the e-commerce carbon footprint dramatically.
• By far the largest source of CO2 in local purchases is the customers driving to and from the store.  Short driving distance, high fuel efficiency, or alternate forms of transit can all shift the balance in favor of shopping locally.
• On the e-commerce side, two potentially large but highly variable factors are the carbon footprint of the product packaging (which Amazon has made efforts to reduce) and the efficiency of the delivery from the local distribution center to the customer’s house.  For instance, having electric or hybrid delivery trucks and efficient scheduling can greatly improve the eco-friendliness of e-commerce.

Of course, there are other reasons besides carbon footprint that may also influence your decision to shop locally vs. online.

What about owning a Kindle or other e-reader?  Obviously, buying an electronic copy of a book eliminates most of the sources of energy expended in buying a print book locally or online.  However, a lot of energy goes into building an e-reader, and also into disposing of old ones.  They take energy to run, as well.  How does all of that compare to the carbon footprint of buying print books?

One well-publicized report by CleanTech concluded that buying your books on a Kindle is more energy efficient than buying (new) books in print, so long as you read 23 books or more per year.  However, Eco-Libris has critiqued this analysis, pointing out that there is too much uncertainty about Amazon’s carbon footprint to know how many books are needed to make a Kindle the greener option.

Eco-Libris also has an extensive collection of articles and other reference material addressing the environmental impact of e-readers more broadly.  While there’s no conclusive answer about the relative greenness of e-books vs. paper books, it clearly makes a huge difference how much you read and whether you buy your paper books new or used.  Unless you are a voracious buyer of books and/or periodicals, it looks like you should not consider the environmental impact as an argument in favor of buying an e-reader.