Closed loop systems minimize waste by keeping materials in the economy and out of landfills and incinerators. Our goal is to close the materials loop, most preferably by keeping environmentally preferred materials in circulation as long as possible. This entails maximizing the reuse and recycling of environmentally preferred materials. Less preferred, but certainly better than landfilling or incinerating plastics, is to biologically degrade them to create soil amendments and feedstocks for new materials (for example, through anaerobic digestion).
For plastics, the ideal is to either create plastics that are easily recycled back into the same product or can be composted into nutrients healthy for the soil. McDonough and Braungart refer to these as technical nutrients (materials that are readily recycled or reused) and biological nutrients (materials that are designed to return biological cycles).
The Plastics Scorecard integrates each these three life cycle principles into the criteria for evaluating and identifying more sustainable plastics.
Green Chemistry in Manufacturing
Closed Loop Material Flows
By implementing each of these principles, the carbon footprint of plastics will be greatly diminished.
1 Institute for Agriculture and Trade Policy and Friends of the Earth. 2008. Sustainable Biomass Principles (accessed July 30, 2008).
2 Paul Anastas and John Warner. 1999. Green Chemistry: Theory and Practice, Oxford University Press: New York.
4 William McDonough and Michael Braungart. 2002. Cradle to Cradle: Remaking the Way We Make Things. New York: North Point Press.