The aim of this study is to identify the different evolution paths of the gas infrastructure in Piedmont region considering, on the one hand, the perspective decrease of natural gas consumptions (according to European and national decarbonization targets for 2030 and 2050) and, on the other hand, the development of the biomethane sector as a distributed source of renewable gas. An optimization model is used to determine the most cost-effective decision that the Transmission System Operator should take about decommissioning or replacement of existing pipelines in the regional gas network. The Piedmontese network has been first represented on GIS software from open-source data.