Konferensartikel

The greenhouse gas (GHG) balance or carbon footprint of biofuels; generally calculated by life cycle assessments (LCA); is heavily influenced by the modeling of land use changes (LUC). This includes direct land use changes (DLUC) and indirect land use changes (ILUC). Various methodical approaches for the integration of ILUC in LCA have recently evolved. In this study several approaches for calculating ILUC and the effects on GHG balance are compared. These are economic modeling; deterministic modeling and regional modeling. Papers published on this topic since 2007; when the ILUC debate began; are reviewed considering the following main criteria: methodological approach; uncertainties of assumptions; and the level of the GHG emissions due to ILUC. The results show that the existing approaches lead to strongly divergent results. This is due to uncertainties about relevant assumptions; e.g. the methods of linking commodity prices to ILUC; assumptions about yields; soil carbon contents; and the effect of by-products. These uncertainties and other methodological inconsistencies; e.g. the allocation issue with respect to displacing vs. displaced crops; imply that further research is needed and that current methods are not robust enough for adoption in regulation.

Biofuels; Greenhouse-gas balance; Life cycle assessment; Indirect land use change; EU policy