Energy and greenhouse gas balance of biofuels: biases induced by LCA modelling choices

Jul 2008

Rapid development of biofuels during last decades has induced strong concerns about possible drawbacks such as deforestation, loss of biodiversity, excessive use of water or scarce resources. in its proposal of 31st January 2007 for a Directive amending Directive 98/70/EC, the European Commission was preparing to require suppliers of fuels for road transport to monitor life-cycle greenhouse gas (GHG) emissions from those fuels and report to the Member States. In its proposal of 23 January 2008 for a Directive on promotion of the use of renewable sources, the European Commission has defined a  floor target of 35% GHG emissions reduction (with respect to fossil fuels) for such fuels that will be eligible to public incentives and account for 10% biofuels target by 2020. In Switzerland, the Federal Government has defined a similar floor target of 40% GHG emissions reduction for biofuels. On ecological merit of biofuels in the world, particularly United Kingdom, the Netherlands and the State of California in US, sustainability standards that are environmentally sound, socially responsible and economically effective are being developed in order to limit GHG promotion. Existing initiatives are described in a technical report by the Laboratory of Energy Systems (LASEN) of the Swiss Federal Institute of Technology of Lausanne (EPFL). Life-cycle assessment (LCA) of biofuels is often limited to energy and/or GHG balance. Several LCA studies have been completed with various frameworks, scopes, accuracy. transparency and consistency levels, making it difficult to compare results on a rational basis, even when addressing same biofuel pathway. LCA methodology (ISO 14040-series) evaluates environmental performance of a product, process or pathway along its partial or whole life cycle.
Present paper investigates to what extent methodological choices can affect results of an LCA, with emphasis on system definition and boundaries, functional unit, reference system and allocation methods, taking fuel-bioethanol production from wheat as base case.

 
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