Energy and environmental assessment of residual bio-wastes management strategies

This paper assesses the potential energy and environmental impacts of an anaerobic digester coupled with a combined heat and power plant powered with bio-wastes from the agri-food sector. The analysis is carried out through the Life Cycle Assessment methodology following a “cradle-to-grave” approach and is based mostly on primary data. The anaerobic digester - combined heat and power plant is analysed considering a twofold perspective: one more energy – oriented where the main function of the system is to generate renewable electricity and a waste – oriented one in which the main function is treating bio-wastes. In addition, the environmental indirect effects related to potential competitive uses of bio-wastes are evaluated. Biomass transport and the electricity consumed during the operation phase make the largest contribution (higher than 60%) to almost all the impact categories examined. The comparison with the electricity eco-profile from the national grid and with a composting facility highlights that the anaerobic digester - combined heat and power system may reach better energy and environmental performances for both the electricity generation and bio-waste management.