Analysis and optimization for energy, cost and carbon emission of a solar driven steam-autothermal hybrid methane reforming for hydrogen, ammonia and power production

Abstract

A novel idea of solar driven steam-autothermal hybrid reforming system (SAHRS) is proposed with onboard carbon capturing system in the existence of carbon emissions taxes. The CO2 produced by the steam methane reforming is employed to the autothermal reforming as input and cryogenic air separation unit is integrated to provide autothermal reforming with oxygen and ammonia synthesis with nitrogen. The autothermal reforming is modified with further integration of water gas shift reactor (WGSR) which converts carbon mono-oxide into carbon dioxide by reacting with steam and this CO2 is captured in the carbon capturing system using aqueous ammonia. Some amount of hydrogen produced by the autothermal reforming is employed to the ammonia synthesis reactor to achieve onboard ammonia for CO2 capture. The system generates enough power to overcome the required power and supply power as a final commodity as well. The present system is essentially designed for cleaner production and industrial applications. The performance indicator for the designed system is defined in terms of energy and exergy efficiencies which are found to be 53.4% and 45.0% respectively. The carbon emissions produced by the system and tax saving by the aqueous ammonia based CO2 capturing are also calculated in the proposed study.