Impact of Biomass on Industry: Using Ethylene Derived from Bioethanol within the Polyester Value Chain

Life cycle assessment has been used to investigate the environmental impacts associated with using ethylene produced from biomass, rather than from the processing of crude oil, in the production of polyethylene terephthalate (PET). The cases investigated were for polymer production and distribution facilities located either (i) in the United Kingdom (UK) or (ii) in the United States of America (USA). For these cases, the ethylene was assumed to be made in Brazil, starting from ethanol made from sugar cane, and subsequently converted to ethylene glycol before shipping. A further comparison was made for the UK-based plant in which ethylene glycol was produced from a hypothetical plant based in the UK using willow as the feedstock. Using the Brazilian ethylene glycol, the net reduction of greenhouse gas emissions, over a process using ethylene glycol from petroleum processing, was similar to 28% when the final product was a 500 mL PET bottle. The accompanying reduction in total use of fossil fuel was similar to 16%. Using ethylene glycol derived from willow biomass in the UK produced similar fossil fuel savings, however, a smaller 3.6% reduction in the greenhouse gases. Comparisons have also been made using other environmental impacts, e.g. acidification and eutrophication, for which the biomass systems are at a disadvantage. An economic assessment of the bioethanol to ethylene conversion process has demonstrated significant dependence on the feedstock cost and product price margin; the analysis suggests that such a process is unprofitable without incentives.