3. Life cycle impact assessment (LCIA) results and interpretation
In this section, life-cycle impacts arising from the considered variations in unit processes associated with feedstock type, biogas utilization, and digestate processing and handling are presented. LCIA midpoint results help to improve the understanding of the complexity of impacts to emissions to air, water and soil to impact categories. Positive values signify increased environmental impacts, whereas negative values signify reduced environmental impacts accrued from substitution of fossil fuels with biogas and chemical fertilizers with nutrients from the digestate (see Fig. 1). Indicated values are given per tonne of feedstock (see also Section 2.2.1.1).