A comparative analysis of the carbon intensity of biofuels caused by land use changes

Abstract

Abstract Worldwide land is a limited resource and its use for the production of biofuels and other agricultural products can impact greenhouse gas emissions ( GHG ). Several models and approaches have been used to assess the direct ( dLUC ) and indirect land use change ( iLUC ) carbon intensity – i.e. the amount of CO 2 emitted per unit of biofuel produced – of biofuels, but their outcomes diverge significantly. This analysis of 15 studies published between 2008 and 2010 (i) summarized and compared models and approaches used to estimate the dLUC and iLUC carbon intensities of biofuels, and (ii) assessed the mechanisms that led to the variation in the outcomes. The data show that the dLUC carbon intensity ranged from −52 to 34 g CO 2 MJ −1 , whereas the iLUC ranged from 0 to 327 g CO 2 MJ −1 for bioethanol depending on the feedstock, on the type of land used or displaced and on the amortization period. The total LUC carbon intensity of bioethanol was found to be −29% to 384% of that of gasoline. This means that in some cases, LUC could potentially alter the GHG benefits of biofuels. Standardizing assumptions, carbon stock changes and methodologies for estimating the dLUC and iLUC carbon intensity will ensure more consistency and meaningful comparisons across studies in the future. This might then enable policy makers to make better justified judgments on the sustainability of biofuels.