2020 年 41 巻 6 号 p. 266-281
Methanation, or methane synthesis, attracts the energy sector in the context of sector integration and climate change mitigation. This study presents a techno-economic assessment on synthetic methane in Japan employing an electricity and city gas supply model. This model, formulated as a linear programming problem, explicitly considers a carbon recycling system, including carbon capture, water electrolysis and Sabatier reaction processes. The electricity and city gas sectors in this model are temporally disaggregated, balancing hourly consumption and supply for a year, to incorporate the intermittent output of solar and wind power (Variable Renewable Energy = VRE) as well as hourly CO2 generation profiles of thermal power plants. Simulation results imply that cost reductions of VRE as well as high carbon prices, such as 75% cost reduction of VRE (from the level in 2014) and 1000 US$/tCO2, would be crucial to boost the deployment of methane synthesis in Japan. Significant amount of VRE capacity would be necessary to decarbonize the both sectors. The results also suggest that water electrolysis and methanation in VRE rich regions, combined with inter-regional methane transportation to demand centers, could be a costefficient option to promote synthetic methane.
