Life-cycle analysis (LCA) or assessment is an internationally renowned methodology for evaluating the global environmental performance of a product along its partial or whole life cycle, considering the impacts generated from "cradle to grave." At its early age, the meth­odology was mainly dedicated to industrial products. Although the ISO 14040-series (ISO, 2006a, b) provides the standard for LCA, it was applied in a variety of ways and thus often leads to diverging results, especially in the case of biofuels. LCA of biofuels is often limited to energy and/or GHG balance. Several LCA studies (ADEME, 2010; ADEME-DIREM-PWC, 2002; Beer and Grant, 2007; CONCAWE-EUCAR-JRC, 2008; Elsayed et al., 2003; EMPA, 2007a; GM-LBST, 2002; Gnansounou and Dauriat, 2004; Macedo, 2004; Malca and Freire, 2006; Shapouri et al., 2002; VIEWLS, 2005; Wang, 2005) have been completed with various frameworks, scopes, accuracy, transparency and consistency levels, making it difficult to compare the results on a rational basis, even when addressing the same biofuel pathway (Panichelli et al., 2008).

The main assumptions found in the literature when estimating the reduction of GHG emissions of biofuels compared to fossil fuels are described in detail in a technical report by the Laboratory of Energy Systems (LASEN) of EPFL (Gnansounou et al., 2008a). Before introducing the general framework of the analyses made in this chapter, a short review of the most significant methodological issues of LCA is proposed, with a focus on the cases of biofuels.