Environmental aspects of eucalyptus based ethanol production and use

Abstract

A renewable biofuel economy is projected as a pathway to decrease dependence on fossil fuels as well as to reduce greenhouse gases (GHG) emissions. Ethanol produced on large-scale from lignocellulosic materials is considered the automotive fuel with the highest potential. In this paper, a life cycle assessment (LCA) study was developed to evaluate the environmental implications of the production of ethanol from a fast-growing short rotation crop (SRC): eucalyptus as well as its use in a flexi-fuel vehicle (FFV). The aim of the analysis was to assess the environmental performance of three ethanol based formulations: E10, E85 and E100, in comparison with conventional gasoline. The standard framework of LCA from International Standards Organization was followed and the system boundaries included the cultivation of the eucalyptus biomass, the processing to ethanol conversion, the blending with gasoline (when required) and the final use of fuels. The environmental results show reductions in all impact categories under assessment when shifting to ethanol based fuels, excluding photochemical oxidant formation, eutrophication as well as terrestrial and marine ecotoxicity which were considerably influenced by upstream activities related to ethanol manufacture. The LCA study remarked those stages where the researchers and technicians need to work to improve the environmental performance. Special attention must be paid on ethanol production related activities, such as on-site energy generation and distillation, as well as forest activities oriented to the biomass production. The use of forest machinery with higher efficiency levels, reduction of fertilizers dose and the control of diffuse emissions from the conversion plant would improve the environmental profile.