Design of an efficient CO2 methanation process and techno-economic analysis with CO2 capture from the flue gas of automotive shredder residue

Recycling and utilizing automotive shredder residue (ASR) is necessary for realizing a sustainable automotive industry. This study conducted a feasibility analysis using a process simulator for Case I, where fuel gas is produced through the gasification of ASR followed by combined heat and power generation using a gas engine, CO2 capture from exhaust gas through chemical absorption, and production of synthetic methane (CH4) using the captured CO2 and renewable hydrogen produced via water electrolysis powered by renewable energy sources. This process produces not only CH4 but also surplus electricity, which can be used to produce H2 or power adjacent equipment. Case II, where fuel gas obtained from ASR gasification was directly methanated, was considered for comparison. This study compared the economic potential of both processes for kiln-type ASR gasification that can process 1,200 kg-ASR/h to produce 3,350 Nm3/h of fuel gas. Case I produced 4,800 tons/ year of CH4 with an energy efficiency of 46.5 %, whereas Case II produced 2,720 tons/year. The levelized production cost of methane in 2050 can be estimated at $1,241/ton and $1,568/ton for Cases I and II, respectively, which are lower than the expected cost of natural gas in market environments by 2050. This study highlights the potential of ASR-derived CO2 methanation as a carbon-neutral technology that can effectively achieve carbon conversion while producing high-value synthetic methane.