LCI Modelling approaches applied on recycling of materials in view of environmental sustainability, risk perception and eco-efficiency

摘要

Two ISO-compatible approaches on modelling the recycling of plastics and metals are frequently applied in life cycle assessment case studies and intensively debated: the recycled content or cut-off approach and the end of life recycling or avoided burden approach. This paper discusses the two approaches from three different perspectives: 1) the kind of sustainability concept served, 2) the risk perception involved and 3) the eco-efficiency indicators resulting from the two approaches. The analysis shows that the recycled content approach serves the strong sustainability concept. It is based on a risk aversive attitude and results in higher eco-efficiency of metal scrap recycling as compared to primary metal manufacture. The end of life recycling approach serves the weak sustainability concept (losses in natural capital can be compensated by man-made capital). It corresponds to a risk seeking attitude and results in higher eco-efficiency of primary metal manufacture as compared to secondary metal production. It is concluded that a harmonisation of the approaches is hardly possible and even not necessary due to the value choices involved. It is the task of (private and public) LCA commissioners to decide on the appropriate modelling approach according to their perspective. National authorities may have a rather long-term and risk aversive perspective while industries may prefer a short term perspective leading them to select the recycled content and end of life recycling approach respectively. Life cycle inventory databases need to be flexible to serve such opposing perspectives and to enable practitioners to adapt the modelling approaches according to the needs of the commissioner. Flexibility is served best by providing unit process LCI data.