Biomethane has drawn significant attention worldwide as one of the few ways to mitigate emissions from natural gas consumption. Spatial biomass assessments are crucial in attracting investors, yet current methods lack a process-oriented perspective for optimising biomethane production and project sustainability. This study introduces a novel process-oriented approach for high-resolution spatial biomass assessments, enabling informed decision-making on site selection, logistics planning and optimising biomethane production. The study was conducted for Queensland, including existing feedstocks, such as sugarcane, cotton, winter and summer crops, manure, and food waste, using ArcGIS 10.8.2 software. The study assesses the aggregate biomass and biomethane potential along with the evaluation of the carbon/nitrogen (C/N) ratio at 1 km2 resolution. Queensland's biomass potential for biomethane production was estimated to be 19 million tonnes (Mt) annually on a dry-matter (DM) basis, with an associated biomethane production potential of 109 PJ/yr. The Overall C/N ratio of total biomass was assessed to be 53:1. The biomethane production potentials within 20, 50, and 100 km from the gas grid were determined at 17, 40, and 69 Peta Joules (PJ)/yr, respectively. The study concludes that 73 % of Queensland's local gas consumption can be met with biomethane using the state's existing biomass resources. This study recommends the extension of the gas grid to optimise the benefits of available feedstocks. The proposed expansion has the potential to significantly enhance biomethane production within 20, 50, and 100 km from the gas grid, yielding annual outputs of 68, 93, and 105 PJ/yr, respectively.