Substitution of Agro-Energetic Biomass with Bio-Waste for an Existing Anaerobic Digestion Plant: An Energetic and Environmental Analysis

Two different scenarios aimed to energy recovery from biodegradable substrates, represented by energy crops and bio-waste, via anaerobic digestion (AD) were compared. In the base scenario 17,1760Mg/year of energy crops were processed in an existing AD facility generating about 7,700 MWh/year whereas 23,000 Mg/year of bio-waste were processed in an existing composting facility for organic fertilizer production. In this case the cumulative energy demand (CED) resulted of 11,000 MWh. In the modified scenario the energy crops were substituted by the bio-waste in the AD facility leading to the generation of about 5,000 MWh/year of energy with a correspondent CED of 8,600 MWh. The life cycle analysis detected an higher impact for the base scenario. On the other hand the amount of kgCO2eq generated per each kWh recovered resulted practically the same for the two scenarios.