A limited LCA comparing large- and small-scale production of ethanol for heavy engines under Swedish conditions

Ethanol is a renewable fuel that can be produced in small farm-scale plants as well as in medium- and large-scale industrial plants for use in e.g. heavy diesel engines. The purpose of this study was to analyse whether the use of a small-scale production system reduced the environmental load in comparison to a medium- and a large-scale system. Therefore, a limited life cycle assessment (LCA), including air emissions and energy requirements, was carried out for the three plant sizes. For the small plant and with physical allocation, the global-warming potential was 31.5 g CO2-eq/MJfuel, the acidification potential was 198 mg SO2-eq/MJfuel, the eutrophication potential was 30.9 mg PO43−-eq/MJfuel, the photochemical ozone creation potential was 13.8 mg C2H4-eq/MJfuel and the energy requirement 359 kJ/MJfuel. It was shown that the differences in environmental impact and energy requirement between small-, medium- and large-scale systems were small. The longer transport distances to a certain degree outweighed the higher energy efficiency and the more efficient use of machinery and buildings in the large-scale system. The dominating production step was the cultivation, in which production of fertilisers, followed by soil emissions and tractive power, made major contributions to the environmental load. The choice of allocation method had a certain influence on the difference between the scales, whereas the influence of uncertainty in input data and of some alternative production strategies was small.