Scenario assessment of implementing methanation considering economic feasibility and regional characteristics

Reducing CO2 emissions is essential for mitigating the effects of climate change. Carbon capture and utilization (CCU) has been considered as a potential strategy for mitigating CO2 emissions, and methanation is one of the most promising CCU technologies which should be investigated for implementation in Japan. In this study, the economic feasibility and CO2 reduction potential of the methanation process in Japan was comprehensively evaluated, considering the country’s regional energy characteristics. Herein, process simulation was employed to optimize a methanation process that can improve the energy efficiency of the entire process, contributing to total CO2 emission reduction. Moreover, to identify the most suitable conditions for the implementation of the methanation in Japan, energy carrier types, CO2 emission sources, plant scales and locations, and international trading partners were comprehensively evaluated. The results show that liquefied CO2 is more economically efficient than liquefied H2 as an energy carrier. Indonesia was identified as Japan’s optimal trading partner. When introducing methanation in Japan, CO2 capture should first be introduced at liquid natural gas (LNG)-fired power plants at a CO2 reduction cost of 474.6–479.8 USD·tCO2−1. In the medium–long term, coal fired power plants is predicted to be the most effective if H2 production cost decrease. A maximum CO2 reduction potential of 293.7 (Mt·y−1) occurs when conducting methanation by CO2 from coal-, BFG-, and LNG-fired power plants in Japan. However, as the domestic supply of renewable energy in Japan is limited, international cooperation is necessary to introduce methanation at a large scale.