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

摘要: Abstract Anaerobic digestion promotes a valorisation of residual and dedicated biomass agricultural origin. The EU Directive 2009/28/CE mandates minimum 35% saving in greenhouse gas (GHG) emission for biofuels bioliquids. National legislations add further limits, such as 70 km maximum distance the supply energy uses (Short chain support scheme Italy). In order to assess if substitution fossil fuels with biogas complies obligations which are factors most influencing GHG savings, simulation study was carried out on digester fed by maize silage, many plants built frame current incentives. A simplified balance drawn between CO2 emitted saved 1000 kWel aimed heat electricity co-generation. output operational radius feedstock digestate disposal allowing standard scenario. sensitivity analysis also run varying several traits concerning process efficiency, characteristics, logistic aspects, plus amount net thermal actually exploited CH4 N2O emissions from stored digestate. scenario involving allowed an 192 km, almost three times large prescribed Short scheme. As alternative, 50% possible at 70 km. Varying process, ±10% determined variations break-even associated saving, ranging ±20% (total solids; volatile anaerobic biogasification potential; content), ±15% (energy efficiency), only ±5% (CO2 cropping phase; carrying capacity transport means). Actual utilisation emissions, respectively set 100% 0% scenario, high uncertainty normal practice. Therefore, respective variation of −50% and +50% adopted analysis, determining both cases strong reduction (50%) distance. overcome critical points represented valorised digestate, special care is needed planning plants, ensure good recycle within process.