Environmental life cycle assessment for rapeseed-derived biodiesel

Biofuels have received special research interest, driven by concerns over high fuel prices, security of energy supplies, global climate change as well as the search of opportunities for rural economic development. This work examines the production of biodiesel derived from the transesterification of crude rapeseed oil, one of the most important sources of biodiesel in Europe, paying special attention to the environmental profile-associated to the manufacture life cycle (i.e., cradle-to-gate perspective). To do so, a Spanish company with an average annual biodiesel production of 300,000 t was assessed in detail. The Life Cycle Assessment (LCA) study covers the whole life cycle, from the production of the crude rapeseed oil to the biodiesel production and storage. The inventory data for the foreground system consisted of average annual data obtained by on-site measurements in the company, and background data were taken from databases. Seven impact categories have been assessed in detail: abiotic depletion, acidification, eutrophication, global warming, ozone layer depletion, land competition, and photochemical oxidant formation. An energy analysis was carried out based on the cumulative nonrenewable fossil and nuclear energy demand as an additional impact category. Furthermore, well-to-wheels environmental characterization results were estimated and compared per ton-kilometer for the biodiesel (B100) and the conventional diesel so as to point out the environmental drawbacks and strengths of using biodiesel as transport fuel in a 28 t lorry. The results showed that the cultivation of the rapeseed was the main key issue in environmental terms (68 %-100 % depending on the category) mainly because of fertilizer doses and intensive agricultural practices required. With regard to the biorefinery production process, pretreatment and transesterification sections considerably contribute to the environmental profile mostly due to electricity and chemical requirements. Concerning the well-to-wheels comparison, using B100 derived from rapeseed oil instead of petroleum-based diesel would reduce nonrenewable energy dependence (-20 %), GHG emissions (-74 %), and ozone layer depletion (-44 %) but would increase acidification (+59 %), eutrophication (+214 %), photochemical smog (+119 %), and land competition. The information presented in this study could help to promote the use of renewable transport biofuels. However, the extensive implementation of biodiesel (particularly rapeseed oil-derived biodiesel) in our society is enormously complex with many issues involved not only from environmental but also economical and social points of view.