Replacing energy crops with bio-waste for an existing anaerobic digestion plant: Energetic and carbon footprint in a LCA perspective

The energetic and greenhouse gases emissions performances related to energy crops substitution with bio-waste for an existing anaerobic digestion (AD) facility were investigated in a life cycle assessment (LCA) perspective. For this reason two different scenarios were compared In the base scenario 17,667Mg/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 separately 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 whole 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 both cases.