Comparison of three common life cycle environmental impact assessment methodologies for polyolefin crates

Abstract

In this thesis, a comparative analysis of three different life cycle impact assessment methodologies has been carried out for polyolefin plastic crates. Additionally, improvement possibilities for the waste management of plastic crates have been investigated. In the study, GaBi 4 software tool was utilized for methodology comparison. The three different life cycle impact analysis methodologies assessed in this study include: CML 2001, EDIP 2003 and Eco-Indicator (EI) 99 – “Hierarchist Approach”. The differences and similarities of the methods were examined. While EI is an endpoint methodology, EDIP and CML are midpoint methods. In the first part of the study, polyethylene (PE) and polypropylene (PP) plastic crates were analyzed with these methods. In the second part, the CML methodology was selected and applied to observe the effect of recycling and incineration on the products’ life cycles. In the comparative analysis, differences of less than 1% were observed in the characterization stage for all methodologies. According to EDIP, the acidification and photo-oxidant formation results slightly favor the use of PP, however, the eutrophication results weakly support PE use. Based on the CML, acidification, photo-oxidant formation and toxicity results approve PP scenarios, whereas eutrophication and global warming results shows PE use as more advantageous. For EI, toxicity results indicate that PP may be favored, however resource depletion and global warming results highlight that PE may be preferred. Thus, it has been concluded that both plastic materials show similar performance. In addition, in global warming and ozone depletion the results do not vary with methodology selection. For other categories, similarities can again be observed. Results also indicate that incorporating recycling into waste management leads to a reduction in emissions. For the comparison of “40% recycling” and “only virgin raw material use” scenarios, it has been deducted that the “40% recycling” scenario achieves a reduction of approximately 39% is achieved in all CML categories. When considering the “60% recycling” scenario, a reduction of about 59% was observed relative to the “only virgin material use” scenario. The reuse of plastics was researched using CML. It has been assessed that a decrease in reuse from 350 times to 300 times led to a reduction of 25.19% in the weighting scores.