raw biogas produced by anaerobic digestion. The anaerobic digestion process (handling and use of substrate, plant operation and use of digestate) was assumed to be identical for all the scenarios assessed and therefore not included in the analysis. However, the fuel production and use of the fuel were included; thus the study had a gate-to-grave modelling approach. The system boundary encompassed the following processes:
• Biogas cleaning and upgrading
• Compression and production of fuel (CBG, LBG, FTD, methanol and
DME)
• Storage, transportation, distribution and fuelling of fuel
• Combustion of fuel in the internal combustion engine of public buses in urban conditions