Energy and economic comparison of SOFC-GT, MCFC-GT, and SOFC-MCFC-GT hybrid systems

Conversion of fossil fuels to electrical power is the most popular method of electrical power generation. Due to the depletion of fossil fuels and the increase in air pollution, the necessity of using high efficiency power generation systems is increasing. High temperature fuel cells, such as solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC), have high efficiency. According to the high operation temperature of these fuel cells, there is the possibility of combination of them with gas turbines (GT) to reach to a higher efficiency. In the present study, the SOFC-GT hybrid system, the MCFC-GT hybrid system, and the new SOFC-MCFC-GT hybrid system are compared from an energy and economic point of view. The results show that the MCFC-GT has the highest efficiency but its annualized cost is greater than the others. The new SOFC-MCFC-GT hybrid system is more efficient than the SOFC-GT hybrid system for low current density, high fuel utilization, and high air utilization. This new hybrid system has lower annualized cost than MCFC-GT hybrid system.