Are Kindles really so green?

A report released last week by the Cleantech Group, a consultancy and analysis outfit, laid out a strong environmental case for the Amazon Kindle and, by extension, all e-readers. The study underscores the stunning positive impact that e-readers could have on our environment should the technology become widely adopted and replace paper as the medium for books, magazines and newspapers.

The report found that "e-readers purchased from 2009 to 2012 could prevent 5.3 billion kg of carbon dioxide in 2012, or 9.9 billion kg during the four-year time period." In other words, treehuggers should be blowing Amazon (AMZN) CEO Jeff Bezos big kisses. But there's a catch, and it's a big one.