Efficient methanol production by combining municipal solid waste gasification, SOEC and methanolation reactor: A thermodynamic study

Hydrogen plays a key role in achieving carbon neutrality goals, while the difficulties in hydrogen storage and transportation hinder the practical deployment of hydrogen energy. Converting hydrogen into methanol is a promising alternative option, given that methanol is currently widely used and the infrastructure is fully established. As for the carbon source, while capturing CO2 from flue gas or air is expensive, using the syngas derived from the gasification of municipal solid waste (MSW) is a promising option. Given the above considerations, we proposed an MSW-to-methanol system for producing methanol using syngas generated from MSW gasification and hydrogen produced via water electrolysis powered by renewable energy. This system integrates an MSW gasifier, a purifier, a solid oxide electrolysis cell (SOEC), and a methanolation reactor. A detailed thermodynamic parametric study is performed to assess the effects of key operating variables, including the gasifier's equivalence air ratio (EAR), the molar ratio of water supplied to the SOEC relative to MSW carbon content (HCR), and variations in operating temperature and pressure. The results show that when the EAR is 0.3 and the HCR reaches 3.0, the energy conversion efficiency and exergy efficiency are maximized, reaching 52.1 % and 43.1 %, respectively, together with a carbon conversion ratio from MSW to methanol of 53.6 %.