Exergetic and exergoeconomic evaluation of an SOFC-Engine hybrid power generation system

Abstract

An SOFC-Engine hybrid power generation system is evaluated using exergetic and exergoeconomic analysis methods to determine measures for improving its efficiency and cost effectiveness. The system is a combination of a solid oxide fuel cell (SOFC) and an internal combustion engine; the engine burns the anode offgas and produces additional power, thus improving the electrical efficiency of the overall system.The exergetic analysis, on the SOFC-Engine hybrid system, identifies the location, magnitude, and sources of thermodynamic inefficiencies (exergy destructions and exergy losses) in the system; the largest exergy destruction takes place within the internal combustion engine, followed by the heat exchangers, and the SOFC stack. Through the exergoeconomic analysis, the cost structure of the SOFC-Engine hybrid system is revealed, and the exergoeconomic factor of each component is quantified. The highest exergoeconomic factor of 93% is observed in the SOFC stack, implying that reducing the equipment cost of SOFC is of high importance to reduce the final product of the overall system. On the other hand, the fuel/water preheater shows the lowest exergoeconomic factor of 7%, meaning that improving its thermodynamic efficiency is more important for that component. Concerning the internal combustion engine, a well-balanced exergoeconomic factor of 52% is calculated.