Degradation based operational optimization model to improve the productivity of energy systems, case study: Solid oxide fuel cell stacks

In the present study a comprehensive thermodynamic model and degradation based optimization framework for energy management of anode supported solid oxide fuel cell (SOFC) stacks are carried out. The optimization framework determines optimum operating conditions to maximize system productivity (energy generation over system lifetime) considering degradation mechanisms. The main degradation mechanisms in anode supported SOFCs are nickel coarsening and oxidation. In this study, the optimum operating conditions regarding these degradation mechanisms to achieve maximum productivity at different target lifetimes are derived. The results show that target lifetime has a significant impact on system productivity and optimum operating temperature and current density. Furthermore, SOFC optimum operating conditions as a function of target lifetime are derived. To show the effectiveness of the developed framework, model outputs are compared with two other operating strategies; a base case strategy that optimizes system operating conditions without considering degradation mechanisms and a strategy based on Department of Energy's (DOE) 2016 fuel cell report. Results illustrated that degradation based optimization is more beneficial for improving the entire performance in long-term operation. For instance, system productivity is 7.4% higher in comparison with DOE strategy during 40,000 h operating lifetime. It is expected that the proposed methodology will lead to more rapid commercialization of SOFC technology.