Conceptual design of a novel hybrid system integrating T-CAES and SOFC-GT

This paper proposes an innovative hybrid system integrating thermochemical compressed air energy storage based on methanol decomposition and solid oxide fuel cell-gas turbine (SOFC-GT) system. During charge process, the compression heat is used to drive decomposition into syngas for achieving physical and chemical hybrid energy storage as well as improving the energy level of the compression heat. During discharge process, the SOFC-GT is employed for power generation to achieve high electrical efficiency of the system. Besides, the waste heat of the system is recovered for heating production to further improve the overall efficiency of the system. The performance assessment of the system is performed by the thermodynamic analysis, and the effects of four key parameters (i.e. pressure ratio of air compressor, operating pressure of methanol decomposition reactor, SOFC operating pressure, and SOFC inlet temperature) on the system performance are investigated by the sensitivity analysis. The results show that the power outputs of the SOFC and GT can reach 278.48 kW and 413.22 kW respectively, and the heating output is 258.38 kW. Accordingly, the round-trip efficiency, exergy efficiency, and heating-to-electricity ratio are 84.59%, 61.02%, and 0.37, respectively. The syngas storage tank has the largest exergy destruction (20.76%), followed by the SOFC (16.20%), afterburner (16.11%), and air heater (11.69%).