The conversion of lignocellulosic biomass to methane is a promising way to distribute a renewable resource as a versatile energy vector in an existing grid. Potentially more efficient than the production of liquid fuels, it can be used as Synthetic Natural Gas (SNG) as automotive fuel or in combined heat and power (CHP) applications at any scale. Based on a detailed thermo-economic process model for the thermochemical production of SNG (Gassner and Maréchal, Biomass and Bioenergy 33 (2009), 1587-1604), the paper addresses the multi-objective optimisation of all relevant technology combinations of the developed general process superstructure with respect to cost and efficiency (see explanatory information). In particular, the paper will discuss the influence of the technological alternatives and its operating conditions on the process design and performance and present the optimal process configurations for the polygeneration of fuel, heat and power at multiple scales.