I agree that the days are long gone that environmental purchasing means subsidizes. I worked on a project for a national retailer back in 2003/4 that has over 3,000 stores in North America. The biggest savings we generated came from a similar project to the Walmart recycling you mention. In their case we advised them to invest $6M into OCC (cardboard) crusher/balers into each of their Regional Distrubtion Centers. We then used the “dead head” capacity in their trucks that delivered clothes to the stores to bring OCC back to the DC’s. Back then we weren’t thinking carbon loads but, including strategic sourcing savings from moving from 100′s of garbage haulers to 7, we reduced their waste removal budget from a $12M cost to a $3M profit.