This paper evaluates the thermodynamic performance and costs of biomethane production plants tailored to the Italian scenario, by comparing the competitiveness of a water wash based biogas upgrading plant against a conventional biogas-to-electricity facility.
The main goals of the article are the following: Report an updated picture of the state-of-the-art of the Italian biogas plants fleet, taking advantage from a database of existing plants collected by LEAP (Laboratorio Energia e Ambiente Piacenza) in the framework of its techno-economic assessment activity performed over the last years; Review and compare the strengths and drawbacks of the commercially available upgrading processes, both from a technical and economic point of view; Identify and model a case study, based on water wash upgrading, which is suitable for the Italian context, simulating heat and mass balances; Carry out a preliminary economic assessment of the biomethane production chain, i.e. from cradle to pipeline, in order to determine biogas upgrading competitiveness.
A typical agricultural feedstock, made of a mixture of corn silage and cattle manure is considered as reference. Moreover, concerning the plant size, two scenarios are analysed, respectively, (i) featuring themost common biogas production rate of the Italian plants (500 Sm3biogas/h, which corresponds to roughly 250 Sm3biomethane/h) and (ii) entailing a biogas production rate more suitable for a biomethane plant (1,000Sm3biogas/h, roughly 500 Sm3biomethane/h).