• The environmental impacts of an anaerobic digestion plant were evaluated. • Sulfur removal caused 96.6% of ozone layer depletion in the system. • Mass- and target-based allocations were tested for plant co-products. • Full allocation to gaseous fuel raised digester impacts by up to 17-fold. Municipal solid waste management is a growing environmental challenge, particularly with the increasing demand for sustainable energy solutions. Anaerobic digestion of organic waste offers a promising waste-to-energy pathway, but its environmental performance requires comprehensive evaluation to guide implementation in regional energy systems like Canada’s. This study investigates whether an industrial-scale anaerobic digestion facility processing municipal organic waste can offer superior environmental outcomes compared to a conventional fossil-based methane generator. Life cycle assessment was conducted using CML-IA Baseline, IMPACT 2002+, and Cumulative Energy Demand methods to compare the environmental impacts of two electricity generation scenarios: anaerobic digestion versus fossil methane combustion. Electricity from anaerobic digestion reduced global warming potential by 90% (0.037 vs . 0.386 kg CO 2 eq/MJ) and fossil energy demand by 95% (0.41 vs . 8.77 MJ/MJ) compared to the methane-fueled system. Sulfur removal accounted for 96.6% of ozone layer depletion. Sensitivity analysis showed that assigning all environmental burdens to the biogas output increased the digester’s impact by up to 17-fold. The findings highlight the importance of optimizing purification processes and allocation strategies to enhance the sustainability of biogas systems. Industrial anaerobic digestion, when properly configured, can offer substantial environmental benefits in waste and energy management.
Soltanian et al. (Tue,) studied this question.