Multiscale analysis through the use of biomass residues and CO2 towards energetic security at country scale via methane production

The growing demand for sustainable energy has driven research into renewable methane production to reduce greenhouse gas emissions and reliance on fossil fuels. Promising feedstocks include lignocellulosic dry residues, wet waste, and captured CO2, converted via gasification, anaerobic digestion, and synthetic processes with renewable hydrogen. This study uses a multiscale approach to compare these sources, incorporating a techno-economic evaluation to identify key performance indicators (KPI) for facilities and renewable energy sources. A facility location pro- blem (FLP) determines plant locations and production capacities, considering material availability and transportation costs. The analysis focuses on the decentralised use of wastes and CO2 from point and diluted sources across Spain, employing an MILP model to optimise waste and CO2 utilisation alongside solar and wind energy systems. Results highlight lignocellulosic dry waste and CO2 captured with MEA from point sources as the most promising options. Sensitivity analysis predicts methane prices between 13.028 �/MWh and 47.216 �/MWh through 2050, requiring substantial investment for full methane self-sufficiency. With carbon taxes, the price could drop to 10.735 �/MWh by 2050, competitive with current natural gas prices.