A struggle between reality and reliability: The uncertainties of including indirect land use change in life-cycle assessments

Sammanfattning: Serious questions have been raised about the environmental impacts of biofuels concerning indirect land use change (ILUC) and this concept may also be applied to other products such as bio-based plastics. The purpose of this study is to identify the uncertainties of including ILUC in life-cycle assessments. This study performed a literature review of journal articles examining ILUC. Including ILUC in LCAs of biofuels may have a large impact on the GHG results, although, the range of the impacts of ILUC estimates is vast. The two main models for quantifying ILUC are computable general equilibrium (CGE/GE) models and partial equilibrium (PE) models, which are both agro-economic models that intertwine economics with geodata. Because this type of land use change is indirect and cannot be directly observed, causality is a main concern for the calculations. ILUC models do not contain detailed enough data and require more data on global land cover to become more reliable. Assumptions that provide a simplified depiction of reality are necessary to make ILUC calculations manageable, however, some of them do not correspond with empirical evidence. Emissions from land clearing are distributed over time in ILUC models and deciding the distribution period is arbitrary, yet it has large impacts on the ILUC results. In the ILUC models currently used, there are many uncertainties that have significant impacts for the final result of GHG emissions and the key uncertainties are causality and data. Considering the uncertainties found in this study, it is reasonable to exclude ILUC from LCAs.