tory data should reconsider production and transport from Russia, as it is a major producer and exporter to Europe. The calculated ranges of uncertainty factors in ecoinvent provide useful information but they are more indications of uncertainties rather than strict 95% intervals, and should therefore be applied carefully.

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Purpose The assessment of biofuels has until now mainly focused on energy demand and greenhouse gas emissions. Only little attention has been given to other impacts, although the general importance of water use for the life cycle assessment (LCA) of agricultural products has been recognized in recent publications. The aim of this work is to assess in detail the water consumption along a biofuel production chain taking into account irrigation efficiencies, levels of water scarcity, and type of feedstock, and to integrate those results in a full LCA. Furthermore, we compare the results for biofuels from various feedstocks and regions with conventional petrol. Methods We calculate the water consumption and overall life cycle assessment results in a case study for the production of methyl ester from irrigated and nonirrigated rapeseed. The results are compared with other irrigated and non-irrigated biofuels based on different feedstocks.Results and discussion Water consumption in biofuel production chains based on non-irrigated crops does not vary greatly and is in the same range as for fossil fuel. In contrast, as a consequence of irrigation, agricultural water consumption dominates the overall results of all irrigated crops. Consequently, the level of water scarcity plays a key role for the LCA results. In our case study, the environmental impacts of methyl ester from irrigated rapeseed in a water-scarce region, measured in aggregated Eco-Indicator 99 scores, are almost doubled by water consumption. Variations in irrigation efficiency, however, are of little influence on the results, as the assessment method used here is based on consumptive water, which depends mainly on the evapotranspiration of the crop. Conclusions The focus on greenhouse gas emissions of the main regulatory schemes neglects other relevant environmental impacts and may provide the wrong incentives. Water consumption may thus become a major concern, offsetting the benefits of biofuel use with respect to climate change.

Introduction In the last years, the use of biomass for energy purposes has been seen as a promising option to reduce the use of nonrenewable energy sources and the emissions of fossil carbon. However, LCA studies have shown that the energetic use of biomass also causes impacts on climate change and, furthermore, that different environmental issues arise, such as land use and agricultural emissions. While biomass is renewable, it is not an unlimited resource. Its use, to whatever purpose, must therefore be well studied to promote the most efficient option with the least environmental impacts. The 47th LCA Discussion Forum gathered several national and international speakers who provided a broad and qualified view on the topic. Summary of the topics presented in DF 47 Several aspects of energetic biomass use from a range of projects financed by the Swiss Federal Office of Energy (SFOE) were presented in this Discussion Forum. The first session focused on important aspects of the agricultural biogas production like the use of high energy crops or catch crops as well as the influence of plant size on the environmental performance of biogas. In the second session, other possibilities of biomass treatment like direct combustion, composting, and incineration with municipal waste were presented. Topic of the first afternoon session was the update and harmonization of biomass inventories and the resulting new assessment of biofuels. The short presentations investigated some further aspects of the LCA of bioenergy like the assessment of spatial variation of greenhouse gas (GHG) emissions from bioenergy production in a country, the importance of indirect land use change emissions on the overall results, the assessment of alternative technologies to direct spreading of digestate or the updates of the car operation datasets in ecoinvent. Conclusions One main outcome of this Discussion Forum is that bioenergy is not environmentally friendly per se. In many cases, energetic use of biomass allows a reduction of GHG and fossil energy use. However, there is often a tradeoff with other environmental impacts linked to agricultural production like eutrophication or ecotoxicity. Methodological challenges still exist, like the assessment of direct and indirect land use change emissions and their attribution to the bioenergy production, or the influence of heavy metal flows on the bioenergy assessment. Another challenge is the implementation of a life cycle approach in certification or legislation schemes, as shown by the example of the Renewable Energy Directive of the European Union.

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