CO2 savings affect the break-even distance of feedstock supply and digestate placement in biogas production

Anaerobic digestion promotes a valorisation of residual and dedicated biomass of agricultural origin. The EU Directive 2009/28/CE mandates a minimum 35% saving in greenhouse gas (GHG) emission for biofuels and bioliquids. National legislations add further limits, such as a 70 km maximum distance in the supply of biomass for energy uses (Short chain support scheme in Italy). In order to assess if the substitution of fossil fuels with biogas complies with such obligations and which are the factors most influencing GHG savings, a simulation study was carried out on a digester fed by maize silage, as many plants built in the frame of the current incentives.