Hydrogen and Electric Power Cogeneration in Novel Redox Chemical Looping Systems: Operational Schemes and Tech-Economic Impact

Chemical looping water splitting (CLWS) has emerged as a promising technology to produce pure hydrogen with CO2 capture in a simple and efficient manner. In this study, new schemes for CLWS characterized using integrated turbine-combined CLWS systems (ITC-CLWS) are presented to accomplish cogeneration of hydrogen and electric power. Using natural gas as a feedstock, the ITC-CLWS processes under ambient and pressurized operating conditions are simulated and analyzed based on the desired riser gas velocities that transport solid particles from the combustor to the reducer. The reactors for the ITC-CLWS processes are designed by considering the gas–solid reaction kinetics and multiphase flow properties. The performance results of the ITC-CLWS processes are compared with those of the standard CLWS process and conventional industrial processes including steam methane reforming (SMR) and autothermal reforming of methane (ATR) for hydrogen production. This study reveals that ITC-CLWS can reduce the electricity requirement and enhance process efficiency. Moreover, a novel operating strategy is conceived to yield hydrogen and electric power in a varied proportion in response to their respective fluctuating needs. Based on the economic analyses of the CLWS/ITC-CLWS, ATR, and SMR processes, the levelized cost of hydrogen in the new ITC-CLWS system can be as low as $1.37/kg ($ in 2018), which is around 15% lower than those of conventional H2 production methods with CO2 capture. Furthermore, an economic sensitivity analysis indicates that the price fluctuations of natural gas and electricity have a significant effect on the H2 production cost for CLWS/ITC-CLWS.