The upper thermal efficiency and life-cycle environmental assessment of nuclear-based hydrogen production via splitting H2S and CO2

Abstract

It is proposed to develop a novel thermochemical cycle using nuclear energy to decompose H2S and CO2, thus producing H2 and CO from acidic gas in petrochemical or coal chemical industries, reducing CO2 emissions and promoting sustainable energy development. The upper limits and significant energy-consuming steps were determined based on two chemical routes of the thermochemical cycle systems 1 and 2. When the enthalpy of the H2S oxidation reaction served as part of the circulating energy input, the values for system 1 and system 2 were 38.7% and 34.3%, respectively. However, if only external energy is considered to satisfy the heat and work required to run the reaction and pump, the thermal efficiency rises to 58.4% and 61.2%, respectively. The life cycle assessment (LCA) was used to investigate the environmental effect of the hydrogen generation process base on the upper thermal efficiency in this study, and the results of the LCA are stated in terms of global warming potential (GWP) and acidification potential (AP). The GWP of systems 1 and 2 was calculated as 2.59 kg CO2-eq/kg H2, 2.54 kg CO2-eq/kg H2, The AP of systems 1 and 2 was calculated as 7.48 g SO2-eq/kg H2 and 9.08 g SO2-eq/kg H2, respectively. This paper assesses the environmental effect of two different hydrogen systems used in manufacturing various subsystems in GWP and AP, and compares them to the life cycle of other hydrogen production pathways.