Integrated direct air CO2 capture and solid oxide electrolyzer for sustainable chemical production: Case studies of methanol and synthesis fuel

This paper presents a comprehensive study of a novel system aimed at producing chemicals from CO 2 captured from the atmosphere by integrating direct air capture (DAC) and solid oxide electrolysis cell (SOEC). Two case studies for the chemical produced were considered: CO 2 to methanol and CO 2 to synthetic fuel (synfuel). All scenarios were based on a DAC system capturing 250,000 tonnes per year of CO 2 from the atmosphere. Using Aspen Plus, the results revealed insights into energy consumption, resource utilization, and economic viability. The system produced 36.4 tonne/hr of methanol and 15.1 tonne/hr of synfuel. Methanol production requires 403 MW of electricity and 10.9 tonne/hr of natural gas, with a specific energy consumption of 26.0 kWh/kg-MeOH. Synfuel production demands higher utility usage of 53.9 kWh/kg-synfuel (360 MW electricity, and 7.09 tonne/hr of natural gas). Economic analysis shows a total annual cost and levelized production cost for methanol of $346 M/year and 1.32 $/kg, respectively; for synfuels, the values are $301 M/year and 2.78 $/kg, respectively. Environmental analysis indicates that the amount of CO 2 captured per product unit is for synfuel 1.88 kg-CO 2 captured/kg-synfuel, and for methanol 0.58 kg-CO 2 captured/kg-MeOH. Using Ontario's grid and natural gas emission factor, emission for methanol production amounts to 31.1 g-CO 2 -eq/MJ-MeOH, while for synfuel, it stands at 5.2 g-CO 2 -eq/MJ-synfuel. However, these emissions can be notably reduced by transitioning to renewable sources of electricity and can even become negative in the case of synfuel when hydropower and wind are used as electricity sources. • A CO 2 direct air capture/SOEC to methanol or synfuel system is proposed. • The system is based on a 250,000 tonne/year of CO 2 captured by DAC. • The system produces 36.4 tonne/hr of methanol and 15.1 tonne/hr of synfuel. • Levelized production costs are 1.32 $/kg MeOH and 2.78 $/kg Synfuel . • Equivalent GHG emissions are 31.1 g CO 2 -eq/MJ-MeOH and 5.2 g CO 2 -eq/MJ-synfuel