t is assumed that the waste papers are post-consumer waste. Therefore, the environmental burdens associated with the processes for the original paper production and uses are not included within bioethanol life cycle system. This assumption is consistent with that in other LCA studies of bioethanol produced from waste papers (Mu et al., 2010).
Fig. 1 shows system boundaries for the bioethanol life cycle. It is divided for convenience into three unit processes: (1) collection and transport of waste papers (U1), (2) conversion of waste papers bioethanol and co-produced electricity (U2) and, (3) distribution and use of bioethanol (E100) in a FFV (U3). Manufacture, maintenance and disposal of the FFV were excluded from the system boundary.