Abstract
Indirect land use change (iLUC) must be considered for bioconversion technologies. These technologies, such as corn-to-ethanol technologies, require land not only for the processing facility but also indirectly require land for the cultivation of the input biomass. There are greenhouse gas (GHG) emissions associated with the transformation of the required land, such as forests or pastures, into cropland for the input biomass. iLUC emissions and effects have been examined on a cursory level in the literature, but deeper analysis is needed. We present an iLUC life cycle optimization model that integrates cutting-edge iLUC modeling techniques with optimization methodology. The model minimizes total GHG emissions, composed of direct and indirect processing emissions as well as iLUC emissions of the chosen biofuel production strategy. A case study considering production of 37.9 BL/y of bioethanol in the U.S. illustrates that iLUC emissions contribute to the life cycle GHG emissions of biofuels, even in optimal scenarios. The minimum realizable iLUC emissions rate is 1.5 g CO2-eq/MJ at this production level using corn stover as a feedstock.
