Proposal and energetic and exergetic evaluation of a hydrogen production system with synergistic conversion of coal and solar energy

In this study, a clean and efficient hydrogen production system with synergistic conversion of coal and solar energy is proposed, and the energetic and exergetic evaluation are carried out. The main feature is that the syngas produced by supercritical water coal gasification contains a large amount of steam and some methane, which is very suitable for steam methane reforming reaction to generate high-purity hydrogen. Through ther-mochemical complementary and chemical recuperative methods, concentrated solar energy and high-temperature flue gas are used to supply reaction heat for the supercritical water coal gasification and steam methane reforming processes, respectively. The results showed that the energy and exergy efficiencies reach approximately 50.15% and 50.81%, respectively, which is an increase of 10.42% and 10.78%. The key reason for the improvement in system performance is that the exergy destruction during gasification and reforming is reduced by 7.81% points. As a result, the hydrogen-rich syngas chemical exergy is approximately 54.27% higher than that of the reference system. In addition, sensitivity analysis is employed to disclose the effect of key pa-rameters on the hydrogen yield, syngas composition and methane conversion rate. This study presents a promising solution for large-scale hydrogen production processes.

Automated summary

This study proposes a clean and efficient hydrogen production system that synergistically converts coal and solar energy, and conducts energetic and exergetic evaluations. By using thermochemical complementary and chemical recuperative methods, concentrated solar energy and high-temperature flue gas are utilized for supercritical water coal gasification and steam methane reforming processes, respectively. The energy and exergy efficiencies increase by 10.42% and 10.78%, reaching approximately 50.15% and 50.81%, respectively. The reduction in exergy destruction during gasification and reforming is the key reason for the improved system performance. Sensitivity analysis reveals the effect of key parameters on the hydrogen yield, syngas composition, and methane conversion rate. This study presents a promising solution for large-scale hydrogen production processes.