Life cycle environmental impacts of substituting food wastes for traditional anaerobic digestion feedstocks

Abstract

In this study, life cycle assessment has been used to evaluate life cycle environmental impacts of substituting traditional anaerobic digestion (AD) feedstocks with food wastes. The results have demonstrated the avoided GHG emissions from substituting traditional AD feedstocks with food waste (avoided GHG-eq emissions of 163.33 CO2-eq). Additionally, the analysis has included environmental benefits of avoided landfilling of food wastes and digestate use as a substitute for synthetic fertilisers. The analysis of the GHG mitigation benefits of resource management/circular economy policies, namely, the mandating of a ban on the landfilling of food wastes, has demonstrated the very substantial GHG emission reduction that can be achieved by these policy options – 2151.04 kg CO2 eq per MWh relative to UK Grid. In addition to the reduction in GHG emission, the utilization of food waste for AD instead of landfilling can manage the leakage of nutrients to water resources and eliminate eutrophication impacts which occur, typically as the result of field application. The results emphasise the benefits of using life-cycle thinking to underpin policy development and the implications for this are discussed with a particular focus on the analysis of policy development across the climate, renewable energy, resource management and bioeconomy nexus and recommendations made for future research priorities.