Biomethanation of biomass-derived syngas is a promising renewable methane production technology with high carbon efficiency, but there is lack of evidence on how process scale-up and biomass cost impact the profitability of full-scale processes. In this study, we developed a set of techno-economic models for the assessment of process competitiveness under several scales and configurations, integrating syngas biomethanation with Powerto- Gas (PtG) services, carbon capture and storage (CCS) and biomethane liquefaction. The results indicate that the incentive mechanism currently supporting biomethane production from anaerobic digestion in Italy would grant profitability for small-scale (6 MWth input) syngas biomethanation plants at biomass costs equal to or below 80 €/t. Under the Danish mechanism, such biomass cost corresponds to 60 €/t. At the currently valid biomass cost of 150 €/t, an 8-MW system delivers a minimum selling price (MSP) of 1.07 €/Nm3 biomethane, but such MSP increases substantially when PtG and CCS are included.