Comparative Evaluation of the Power-to-Methanol Process Configurations and Assessment of Process Flexibility

Abstract

This paper compares different power-to-methanol process configurations encompassing electrolyser, adiabatic reactor (s) and methanol purification configurations. Twelve different power-to-methanol configurations based on direct CO2 hydrogenation with H2 derived from H2O-electrolysis were modelled, compared, and analysed. High temperature solid oxide electrolyser is used for hydrogen production. Fixed bed reactor is used for methanol synthesis. The aim of the paper is to give detailed comparison of the process layouts under similar conditions and select the best performing process configuration considering the overall methanol production, carbon conversion, flexibility, and energy efficiency. ASPEN PLUS® V11 is used for flowsheet modelling and the system architectures considered are the open loop systems where methanol is produced at 100 kton/annum and sold to commercial wholesale market as the final purified commodity. Further optimization requirements are established as targets for future work. Three options of power-to-methanol configuration with methanol synthesis from CO2 hydrogenation are proposed and further evaluated considering process flexibility. From the evaluation, the series-series based configuration with three adiabatic reactors in series performed better in most parameters including the flexible load dependent energy efficiency.