Technoeconomic and Environmental Assessments of CO 2 Methanation and Liquefaction for Climate Mitigation

Climate change driven by significant anthropogenic greenhouse gas emissions necessitates accelerating the decarbonization of the energy system. The power-to-X strategy has emerged as a promising pathway to convert renewable electricity into carbon-neutral energy carriers. Synthetic natural gas is an attractive solution due to its compatibility with existing natural gas infrastructures and widespread end-use applications. In this work, a technoeconomic and environmental analysis of liquefied synthetic natural gas production via CO2 methanation is conducted. The analysis focuses on evaluating the economic feasibility and environmental impact of the methane derived from green H2 and captured CO2 in multiple renewable electricity supply scenarios as well as future cost-reduction pathways. Such feasibility indicators are systematically assessed in different renewable electricity supply scenarios to investigate the climate mitigation potential. The assessment is conducted within a cradle-to-gate system boundary covering the production, liquefaction, and storage of synthetic natural gas, with conventional fossil-based natural gas used as the baseline for comparison. The results demonstrate that power-to-methane can show a wide cost range (76. 0 to 109. 0 GJ–1), which is dependent on electricity prices. Further, it can achieve competitive environmental performances (approximately 0. 015 tonCO2-eq GJ–1) and represents a feasible alternative to fossil-based natural gas under favorable renewable electricity integration. This study highlights the potential role of synthetic natural gas as a sustainable energy carrier for long-term climate mitigation.