Energy, exergy and economic (3E) analysis of a high-efficiency reversible solid oxide cell system integrated with thermal energy storage

With the increasing penetration of renewable energy into modern power grids, the inherent intermittency and variability of these resources have become major obstacles to reliable energy supply. To address this challenge, a 120 kW-class reversible solid oxide cell (rSOC) system integrated with thermal energy storage (TES) is proposed. A waste heat recovery loop is incorporated to alleviate the thermal imbalance between the two modes. Aspen Plus process simulation coupled with a detailed electrochemical model is employed to assess the thermodynamic performance of the system in terms of energy and exergy efficiencies. The results show that the proposed rSOC system achieves an energy efficiency of 60.40% in the SOFC mode and 88.83% in the SOEC mode, with corresponding exergy efficiencies of 59.49% and 89%, respectively. Furthermore, techno-economic analysis indicates that the system achieves an LCOH of 3.49 $/kg. The TES unit supplies 55.6% of the additional energy demand during SOEC operation, thereby increasing the energy efficiency of this mode by 15.04%. Exergy destruction is primarily concentrated in the stack and air-side heat exchangers. Parameter analysis reveals that an inlet temperature of 850 °C maximizes SOFC mode efficiency. Additionally, increasing the fuel utilization ratio significantly enhances efficiency in both operating modes.