Ireland's 2015 Energy White Paper proposes the guidelines for a radical transformation in the energy sector in Ireland and a large reduction of CO2 emissions from 2015 to 2050. Biomass-derived synthetic natural gas (bio-SNG) via gasification and methanation (GaM) represents a potential route to decarbonise the use of natural gas. This work presents the initial assessments of suitable resource availability and performs GIS-based (Geographic Information System) mapping of them. The ultimate goal of the work is to design a GaM-based bio-SNG production and distribution network that is environmentally and economically sustainable. Results show that GaM has the potential to meet Ireland's energy targets utilising wastes, residues and energy crops grown exclusively on low-value marginal land. The potential key role of energy crops on marginal land is highlighted for further study. Future steps of the work will involve uncertainty quantification, full life cycle assessment and techno-economic analysis of the proposed system.