Utilizing residual biomasses from agriculture and forestry: Different approaches to set system boundaries in environmental and economic life-cycle assessments

Abstract

Utilizing residual biomass resources in industrial processes has become a major topic in the scientific and political discourse about the bioeconomy. Especially residues from agriculture and forestry play an important role in the future bioeconomy since there are significant utilizable resource potentials and various high-value product opportunities. However, these resources contain valuable plant nutrients and can be important for soil organic carbon balancing wherefore large amounts of these residues currently remain on the cultivation area to maintain the soil health and fertility. To ensure a sustainable resource provision it is necessary to address the various trade-offs by integrating them into appropriate assessment methods.A review of 162 included studies shall reveal how environmental and economic Life Cycle Assessment (LCA) studies handle the multi-functionality of agricultural and forest production systems and address the various effects from an extraction. The main findings can be summarized as follows.•There is no unified method to quantify the life-cycle environmental or economic effects from the utilization of residual biomasses from agriculture or forestry, but rather four basic approaches of system boundary settings.•Individual LCA results from the literature are not cross-comparable due to the different system boundary settings, leading to high uncertainties regarding the actual life-cycle impacts of a technical utilization.•Several aspects of a sustainable resource extraction remain neglected by any of the studies, e.g. effects of a soil organic carbon build-up on soil fertility, soil biodiversity, and crop yields or displacement effects when residual biomasses are currently used for other purposes.