Thermo-economic evaluation of a solar and SOFC-based power and freshwater co-production system

Abstract

Fuel cell has been proved as one of the most efficient energy conversion technologies, while investigations on energy and economic feasibility of advanced energy systems integrated with fuel cells and renewable energy are still needed. This study proposes a novel co-production system mainly coupled with a proton exchange membrane electrolyzer, a solid oxide fuel cell, a multi-effect desalination unit, and a dual pressure organic Rankine cycle to pursue cleaner productions of electricity and freshwater. The system feasibility is evaluated by using energy, exergy, and economic analysis methods. The thermo-economic analysis result indicates that the system energy and exergy efficiencies under basal scenario are 61.06 % and 40.83 %. The power and freshwater productions are found to be 200.1 kW and 0.264 kg/s with the levelized cost rates of 0.0628 $/kWh and 0.0132 $/kg. Parametric study is conducted to reveal the effects of system core parameters on system performance. The analysis result illustrates that the system thermodynamic performance is conflicted with the desalination and economic performance when key parameters are adjusted. To balance the performance conflicts, multi-objective optimization is further performed to obtain optimal system performance in different working scenarios. The optimization result demonstrates that the highest system energy and exergy efficiencies are obtained in scenario A of first optimization, which are 11.46 % and 11.24 % higher than the basal scenario. The highest freshwater production is obtained in scenario C of second optimization with the value of 0.391 kg/s, while the total exergy efficiency and power output are the lowest.