Thermodynamic and environmental impact assessment of steam methane reforming and magnesium-chlorine cycle-based multigeneration systems

In this study, thermodynamic analyses and environmental impact assessments of two integrated systems are comparatively performed for multigenerational applications. The first system consists of a heliostat solar heat and power generation field as energy source, a magnesium-chlorine (Mg-Cl) hybrid thermochemical cycle for hydrogen production, a steam Rankine cycle for power production, and a LiBr-water absorption chiller cycle for space cooling application. The second system is same as the first system except that the steam methane reforming (SMR) which considered for hydrogen production instead of Mg-Cl cycle. The SMR method is commonly used to produce hydrogen; however, it has disadvantages such as releasing CO2 emissions and utilizing fossil fuels for reforming. Mg-Cl cycle can be considered as a promising thermoelectrochemical cycle for water splitting because of its simplicity and applicability as well as possessing higher energy and exergy efficiencies and stability of chemical reactions throughout the cycle. Comparative energy and exergy performance assessments of both integrated systems are performed, and their assessment results are presented and discussed. In addition to the performance evaluation, environmental impact and sustainability assessments of both integrated systems are performed. Furthermore, the study compares two hydrogen production systems in terms of their performances and environmental impacts at varying conditions. Energy and exergy efficiencies of the present systems are found to be 28.4-18.4% for the system I and 43.2-27.4% for the system II, respectively. Exergetic sustainability of SMR-based system is higher than that of Mg-Cl-based system. However, Mg-Cl system does not emit greenhouse gases during production and is more environmentally benign in terms of greenhouse gas emissions. Copyright (c) 2015 John Wiley & Sons, Ltd.