This paper documents a techno-economic assessment of biomethane feedstocks from urban, rural, and coastal settings. Additionally, the effect of three upgrading technologies was investigated, ranging from commercialised systems (water scrubbing) to more advanced systems: power to gas systems employing hydrogen to capture CO2; and microalgae cultivation utilising CO2 in biogas. In total, nine scenarios were investigated based on a combination of the three feedstock groups and the three upgrading technologies. The levelized cost of energy and the incentive required to allow financial sustainability were assessed. The assessment showed that water scrubbing was the cheapest upgrading method. The optimum scenario was the combination of urban based feedstock (food waste) with water scrubbing upgrading costing 87€/MWh, equivalent to 87c/L diesel equivalent. The incentive required was 0.13 €/m3 (or per L of diesel equivalent), however if power to gas was used to upgrade, an incentive of 0.40 €/m3 was required. This was expected as food waste attracts a gate fee. Rural-based plants (using slurries and grasses) are expected to provide the majority of the resource however, for this to become a reality incentive in the range 0.86–1.03 €/m3 are required.