Analyse du cycle de vie axee sur les consequences d'un biocarburant de deuxieme generation a base de saule

This Master's project focuses on the assessment of the potential impacts of a new biofuel resource: willow, grown for energy purposes. This study has been conducted following two main steps. First, an attributional Life Cycle Assessment (A-LCA) on cellulosic ethanol made from willow was performed. Then, a consequential LCA (C-LCA) was carried out using a system expansion regarding the consequences related to a change in land use. Despite the growing interest in biofuels, they still face major criticism. While some biomass resources have shown a net benefit in terms of climate change reduction, the impacts on human health remain debatable. Moreover, these analyses are often controversial and criticised for being too theoretical. Additionally, aside from biomass that competes with food production (corn, sugar beet, rape), some other types of biomass can increase pressure on land availability.;The project hypothesis is that the C-LCA clearly changes the results obtained for E85 made from Canadian willow cellusosic ethanol. While uncertain, this more thorough analysis avoids additional issues since the impacts of land use changes are taken into account.;The methodological choice of using a system expansion is an important issue since there is still no consensus. Two options are currently available including using an approach considering the analysis of scenarios or the use of macroeconomic models. Whereas the use of models seems less theoretical, they are nevertheless time-consuming and complex. Since this project is the first step towards a more thorough analysis, the scenarios approach was selected for this study. In his work, Schmidt (2008) analyzed the possible outcomes of a lack of wheat in Denmark using six scenarios. Likewise, the ways of compensating a lack of corn in Canada need to be analyzed. A link can be made between both studies. This methodology was hence chosen to establish the effects of changing corn cultivation by a willow one. This method appears to be an interesting approach for a C-LCA, as it considers the general ideas that underline it, namely that economy and different constraints play key roles in identifying the affected processes.;This project presents the work performed thus far in order to achieve a more exhaustive study. The innovating part remains in the fact that both approaches, A-LCA and C-LCA are studied and compared. The first results, stemming from the attributional analysis, show that willow-produced E85 could be an alternative to gasoline to reduce climate change or the consumption of non-renewable resources. However, this E85 generates more impacts on human health and on ecosystem quality. This study shows that applying a system expansion leads to a significant change in the study results. While impacts on human health were slightly higher (+1,5% compared to A-LCA), they significantly decreased for ecosystem quality (-42%). These major changes in the results lead to new conclusions: E85 now appears as a better alternative than gasoline to preserve ecosystem quality. This method, in spite of being a simplified version of more complex interactions in crop markets, adds pragmatism to this study and validates the research hypothesis that results can markedly differ when a system expansion is applied. (Abstract shortened by UMI.);This project has two main objectives. The first is to evaluate and to introduce the potential impacts of this new biofuel: the Quebec-based E85 made from willow, an increasingly studied biomass. The second objective is to provide a more realistic analysis by realising a C-LCA, taking into consideration the indirect land use change, and to compare these results with the A-LCA.