Life Cycle Assessment and Green Design: An Assessment of Green Design in a Case Study of Plastics

摘要

In this thesis, a cradle-to-gate life cycle assessment (LCA) for the production of bio-based polyethylene terephthalate (B-PET) is completed and then used along with LCAs of 11 other packaging plastics to evaluate the efficacy of green design principles such as the "12 Principles of Green Chemistry," the "12 Additional Principles of Green Chemistry," and the "12 Principles of Green Engineering."The chemical composition of B-PET is identical to traditional polyethylene terephthalate (PET) and the production methods for both polymers are similar. B-PET production differs from traditional PET production by using (in part) sugarcane molasses as a material source in place of natural gas and petroleum. Results from this study show that B-PET production, compared to PET, represents a 28% reduction in global warming potential and a 12% reduction in non-renewable energy (NREU) use. However, a normalization of impacts in all categories using estimates of total U.S. emissions in 1999 shows that the magnitudes of both reductions are small when compared to increases in human health and exotoxicity impacts. Adhering to green design principles was shown to decrease life cycle environmental impacts for petroleum based polymers and bio-polymers separately. Biopolymers rank highly in terms of green design, however cause increases in life cycle environmental impacts from production in almost every measureable category. This thesis recommends qualifying the "use renewable sources" principle to exclude agriculture products shown to have large, deleterious environmental impacts during farming. Both the use of renewable sources and the design products that biodegrade should be qualified to avoid increasing the number of chemical processing steps to achieve each goal.This thesis does not criticize the inclusion of green chemistry and other green design principles into national research policies or marketing initiatives. It instead uses a case study to evaluate the effectiveness of previously used design principles, outlines possible issues, and makes recommendations for improvements.