I took a lot of heat a few years ago when I said it probably made more sense to pitch many recyclable materials in land fills rather than consume energy in recycling them:
http://community.machinedesign.com/forums/thread/1458.aspx
Now there's validation of this viewpoint from researchers in Singapore and Switzerland. They say biofuels, such as cellulosic ethanol derived from processed urban waste, may offer dramatic emissions savings without the environmental catch.
"Our results suggest that fuel from processed waste biomass, such as paper and cardboard, is a promising clean energy solution," said study author Associate Professor Hugh Tan of the National University of Singapore.
You can read more about it in an item posted on Pysorg.com:
http://www.physorg.com/news173440496.html
The journal article itself is available online, but unfortunately you'll have to pay to view it if you don't subscribe: