The increasing number of biogas plants, especially of those larger than 500 kWe (electrical power), involves a high consumption of energy crops, large transport distances of biomass and digestate and difficulties on thermal energy valorization.
In this study the energetic (CED) and environmental (GHG emissions) profiles associated with the production of electricity derived from biogas have been identified. Three biogas plants located in Northern Italy have been analyzed. The study has been carried out considering a cradle-to-grave perspective and thus, special attention has been paid on the feedstock production and biogas production process. The influences on the results taking into account different plant sizes and feeding rate has been assessed in detail.
Energy analysis was performed using the Cumulative Energy Demand method (CED). The climate change was calculated for a 100-year time frame based on GHG emissions indicated as CO2 equivalents (eq) and defined by the .
In comparison to the fossil reference system, the electricity production using biogas saves GHG emissions from 0.188 to 1.193 kg CO2eq per kWhe. Electricity supply from biogas can also contribute to a considerable reduction of the use of fossil energy carriers (from ? 3.97 to 10.08 MJfossil per kWhe). The electricity production from biogas has a big potential for energy savings and reduction of GHG emissions. Efficient utilization of the cogenerated heat can substantially improve the GHG balance of electricity production from biogas.