Techno-economic and carbon emission analyses of a methanol-based international renewable energy supply chain

Abstract

To achieve a sustainable future, the adoption of renewable energies is crucial. The uneven global distribution of renewable energy necessitates efficient cross-border transportation methods. This study proposes an electricity-hydrogen-methanol-hydrogen-electricity system that utilizes methanol (MeOH) as a renewable energy carrier, facilitating the transport of green energy across borders. Our approach includes Aspen Plus plantwide simulation of MeOH synthesis, MeOH reforming, H2/CO2 separation and purification, and CO2 liquefaction processes. We evaluate each process's material balance, energy consumption, and economic evaluation, encompassing water electrolysis, MeOH/CO2 transportation, and fuel cells electricity generation. Our calculations of current, near future and sustainable future scenarios demonstrate that 10.3–8.5 MWhe of green electricity is required for electrolyzing water to produce 0.196 tonnes of hydrogen, which is then used for synthesizing MeOH (1 tonne). The imported MeOH is reformed in the importing country, recovering 94 % of hydrogen (0.184 tonnes), contributing 2.0–2.9 MWhe of electricity to the grid. The solar and wind supply chains have the CO2 emissions of 575-365 kg/MWhe and 385-257 kg/MWhe respectively. The cost ranges of imported renewable electricity, MeOH and H2 vary depending on the price of exporting renewable electricity, the capital costs, and the operating efficiencies of electrolyzers and fuel cells. These factors contribute to USD 494-106/MWhe for renewable electricity, USD 684-201/t for MeOH and USD 5,199-1,993/t for H2 in the importing countries.