Exergy analysis of reversible sofc coupled with organic Rankine cycle and hydrogen storage for renewable energy storage

Abstract

Due to the ever-rising demand for energy and the need to address the critical issue of global warming, the focus on efficient energy systems driven by renewable energy has gained a lot of attention. Integrating fuel cells with renewable energy is a very attractive and promising solution to achieve this aim. In this study, a novel tri-generation system is presented and analysed for its exergetic performance. A Metal hydride hydrogen storage (MHHS) system is used in the study to supply hydrogen to the Solid oxide fuel cell (SOFC). In the ORC cycle, n-octane is selected as the working fluid due to its high critical temperature. Exergy analysis of the overall system helps in finding out the system components where the most energy is getting degraded. For the analysis, the exergy efficiency pertaining to net electrical power output, heating and cooling performance and tri-generation is considered as the basis of exergy assessment. MATLAB is used to develop a steady-state Parametric analysis is performed by varying the important parameters such as SOFC current density, SOFC temperature and pressure at the turbine inlet. As per the outcome of the present study, the maximum exergy efficiency was reported to be 46.5% at specific operating conditions. The ORC evaporator, heating application and fuel heat exchanger were the major sites for the exergy destruction with values of 258 kW, 175 kW and 91 kW respectively. Also, a maximum gain in exergy efficiency of around 17.4% was reported after incorporating a tri-generation system instead of power cycle alone.