Biomass is a sustainable alternative to fossil energy carriers which are used to produce fuels, electricity, chemicals, and other goods. At the moment, the main biobased products are obtained by the conversion of biomass to basic products like starch, oil, and cellulose. In addition, some single chemicals and fuels are produced. Presently, concepts of biorefineries which will produce a multitude of biomass-derived products are discussed. Biorefineries are supposed to contribute to a more sustainable resource supply and to a reduction in greenhouse gas emissions. However, biobased products and fuels may also be associated with environmental disadvantages due to, e.g. land use or eutrophication of water. We performed a Life Cycle Assessment of a lignocellulose feedstock biorefinery system and compared it to conventional product alternatives. The biorefinery was found to have the greatest environmental impacts in the three categories: fossil fuel use, respiratory effects, and carcinogenics. The environmental impacts predominantly result from the provision of hydrochloric acid and to a smaller extent also from the provision of process heat. As the final configuration of the biorefinery cannot be determined yet, various variants of the biorefinery system were analysed. The optimum variant (acid and heat recoveries) yields better results than the fossil alternatives, with the total environmental impacts being approx. 41% lower than those of the fossil counterparts. For most biorefinery variants analysed, the environmental performance in some impact categories is better than that of the fossil counterparts while disadvantages can be seen in other categories. (C) 2009 Elsevier Ltd. All rights reserved.