Multi-criteria sensitivity study and optimization of an electricity/cooling/hydrogen production scheme combined with SOFC-based sequential heat recovery: Sustainability and economic analyses

The establishment of new multigeneration processes is comparable and assessable from the sustainability viewpoint. Indeed, the sustainability approach assists the economic analysis leading to appropriate combination methods. Concerning the energetic flow exhausting a solid oxide fuel cell system, this study proposes an innovative trigeneration process with high sustainability index utilizing three stages of sequential heat recovery. The process encompasses a two-stage Rankine cycle boosted by a thermoelectric generator and an ejector refrigeration unit, and a polymer electrolyte membrane electrolyzer. This system is simulated in engineering equation solver software and a comprehensive sensitivity study is accomplished. It is concluded that the most influential parameter in the whole framework is the operational temperature of the stack and in the integrated process is turbine 1 pressure. Afterward, an advanced evolutionary optimization method is employed using the MATLAB software, and the optimal point is designated from the sustainability and economic standpoints. The optimal state reveals the sustainability index of 2.61 and total unit cost of 35.93 $/GJ, improved by 12.5% and 3.8% against the base case, respectively. Besides, the electric power, cooling, and hydrogen are correspondingly produced at 389.4 kW, 112.4 kW, and 0.45 kg/h, resulting in exergy efficiency and exergoeconomic factor of 57.75% and 52.1%, respectively.