Resources, Conservation and Recycling 55 (2010) 34–52 Contents lists available at ScienceDirect Resources, Conservation and Recycling journal homepage: www.elsevier.com/locate/resconrec Open-loop recycling: A LCA case study of PET bottle-to-fibre recycling Li Shen a,∗ , Ernst Worrell b , Martin K. Patel a a Department of Science, Technology and Society, Faculty of Science, Utrecht University, Heidelberglaan 2, 3584CS Utrecht, Netherlands b Department of Innovation and Environmental Sciences, Faculty of Geosciences, Utrecht University, Netherlands article info Article history: Received 11 December 2009 Received in revised form 30 June 2010 Accepted 30 June 2010 Keywords: PET recycling Open-loop recycling PET bottle Flake LCA Environment impact Mechanical recycling Chemical recycling GHG emissions abstract This study assesses the environmental impact of polyethylene terephthalate (PET) bottle-to-fibre recy- cling using the methodology of life-cycle assessment (LCA). Four recycling cases, including mechanical recycling, semi-mechanical recycling, back-to-oligomer recycling and back-to-monomer recycling were analysed. Three allocation methods are applied for open-loop recycling, i.e. the “cut-off” approach, the “waste valuation” approach and the “system expansion” approach. Nine environmental impact indicators were analysed, i.e. non-renewable energy use (NREU), global warming potential (GWP), abiotic depletion, acidification, eutrophication, human toxicity, fresh water aquatic ecotoxicity, terrestrial ecotoxicity and photochemical oxidant formation. The LCA results are compared with virgin PET fibre and other com- modity fibre products, i.e. cotton, viscose, PP (polypropylene) and PLA (polylactic acid). The LCA results show that recycled PET fibres offer important environmental benefits over virgin PET fibre. Depending on the allocation methods applied for open-loop-recycling, NREU savings of 40–85% and GWP savings of 25–75% can be achieved. Recycled PET fibres produced by mechanical recycling cause lower environmen- tal impacts than virgin PET in at least eight out of a total of nine categories. Recycled fibres produced from chemical recycling allow to reduce impacts in six to seven out of a total of nine categories compared to virgin PET fibres. Note that while mechanical recycling has a better environmental profile than chemical recycling, chemically recycled fibres can be applied in a wider range of applications than mechanically recycled fibres. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Polyethylene terephthalate (PET) bottles have experienced rapid growth since the 1970s when the technique of blow mould- ing was introduced (Glenz, 2007). Today, bottle grade PET is one of the most important packaging plastics. In 2007, the worldwide consumption of bottle grade PET was 15 million met- ric tonnes (10 6 metric tonnes or Mt) (Simon and Schnieders, 2009), representing 8% of the total demand of standard plastics. 1 Meanwhile, recycling of post-consumer PET bottles has become a well-established system with its own logistic chain includ- ing bottles collection, flake production and pellet production. In 2007, approximately 4.5 Mt of PET bottles were collected and recycled into 3.6 Mt of flakes worldwide (Thiele, 2009). Most of the recycled PET flakes were converted into fibres ∗ Corresponding author. Tel.: +31 30 253 7600; fax: +31 30 253 7601. E-mail address: l.shen@uu.nl (L. Shen). 1 According to PlasticsEurope’s definition, “Standard Plastics” refer to stan- dard thermoplastics, including PE (polyethylene), PP (polypropylene), PVC (polyvinylchloride), PS (polystyrene), EPS (expanded polystyrene) and PET (bottle grade). (Fig. 1). Recycled PET fibre accounted for approximately 8% of the world PET fibre production in 2007 (JCFA, 2008; Thiele, 2009). In Europe, the amount of collected post-consumer PET bottle waste has increased from 0.2 Mt in 1998 to 1.26 Mt in 2008 (Petcore, 2008), representing an annual growth rate of approximately 19% (see Fig. 2). About 40% of all used PET bottles in Europe were col- lected for recycling in 2009 (PlasticsEurope, 2009a). It is expected that PET bottle waste collection in Europe will continue to increase by 10% p.a. in the near future (Glenz, 2007) (see Fig. 2). The primary purpose of this study is to understand the envi- ronmental impacts of recycled PET fibre compared to virgin PET. Several studies reported the environmental impacts of PET recy- cling (Arena et al., 2003; Detzel et al., 2004; Song and Hyun, 1999). In these studies, PET recycling was seen as a post-consumer waste management option and was compared with other options such as landfilling and incineration. The goal of this study is not to anal- yse different waste management options, but to understand the environmental impact of making recycled PET fibres. The second purpose of this study is to apply different alloca- tion methods for this open-loop-recycling case. In LCA, there has been so far no standardised procedure for open-loop recycling. Sev- eral studies have discussed this methodological problem (Ekvall, 0921-3449/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.resconrec.2010.06.014