Modelling synthetic methane production for decarbonising public transport buses: A techno-economic assessment of an integrated power-to-gas concept for urban biogas plants

•A dynamic model for discrete event simulations of PtG technology was built.•Constrained power availability (12 h/d) increased gas production costs by 20%.•Increasing production capacity from 0.75 to 2.25 MWth decreased costs by 16%.•TCO of buses fueled with synthetic CH4 was always higher than diesel.•Synthetic CH4 as drop-in fuel showed lower TCO when CNG prices are high.