Vermicompostaje

Int J Life Cycle Assess (2010) 15:284–293 DOI 10.1007/s11367-010-0162-9

PACKAGING SYSTEMS

Environmental impacts of conventional plastic and bio-based carrier bags
Part 1: Life cycle production
Hsien Hui Khoo & Reginald B. H. Tan & Kevin W. L. Chng

Received: 24 March 2009 / Accepted: 16 June 2009 / Published online: 13 February 2010 # Springer-Verlag 2010

Abstract Background, aim,and scope The use of bio-based products as carrier bags, packaging materials, and many other applications has been increasingly replacing conventional polymer products. One of the main driving forces of bioplastic applications is the perceived depletion and scarcity of fossil fuels, especially petroleum. However, despite being introduced as an environmentally friendly alternative to plastics madefrom crude oil, the environmental benefits of bio-plastics remain debatable. This article serves to investigate whether or not bio-based materials are environmentally friendlier options compared to plastics and attempts to explain the rationale of the results. Materials and methods The production and disposal of both conventional plastic and bio-plastic carrier bags are investigated using life cycleassessment or LCA. A typical bio-based bag (made from polyhydroxyalkanoate or PHA) from the U.S. was selected to be compared with a locally produced polyethylene plastic (PP) bag in Singapore. In the LCA system, the raw materials for making polyethylene came from crude oil imported from Middle East and natural gas piped from Natuna gas field. The refinery and PP bag production processes are basedin Singapore. Bio-bag production was entirely in the U.S., and the finished product was shipped to
Part 2: end-of-life options H. H. Khoo (*) Institute of Chemical and Engineering Sciences (ICES), 1 Pesek Road, Jurong Island 627833, Singapore e-mail: khoo_hsien_hui@ices.a-star.edu.sg R. B. H. Tan : K. W. L. Chng Department of Chemical and Biomolecular Engineering, National University ofSingapore, 4 Engineering Drive, Kent Ridge 117576, Singapore

Singapore. The impact assessment results were generated for global warming potential, acidification, and photochemical ozone formation. Next, normalized results were calculated according to the parameters of Singapore’s annual emission inventory. Results The total environmental impacts of bio-bags showed considerable differences under variousenergy scenarios. When the energy expenditures to make bio-bags are supplied by U.S. electricity mix, the production impacts are about 69% higher, compared to the impacts from PP bags. With coal-fired power supply, the production impacts from biobag production turned out to be about five times greater than those from conventional plastics. The life cycle production impacts of PP bags arecomparable to bio-bags when the energy supplied to the bio-material production chain is supplied by natural gas. Bio-bags are 80% more environmentally friendly than plastic bags when clean and renewable energy (geothermal) is used throughout its life cycle production stages. Discussions and conclusions By the use of LCA with different energy scenarios, this article sheds some light on the extent ofenvironmental benefits (or drawbacks) of replacing plastic carrier bags with PHA bags. It was concluded that the life cycle production of bio-bags can only be considered as environmentally friendly alternatives to conventional plastic bags if clean energy sources are supplied throughout its production processes. It was also highlighted that the results should not be viewed as a global representativesince the case study scope was for Singapore alone. Additional work by others on different biodegradable and compostable bags vary in results. Some of the complexities of such work lie in what is included or excluded from the scope and the adoption of different environmental impact assessment methods. Nevertheless, the authors’ attempt to compare the two bags may serve as a basis for

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