Molten carbonate fuel cell integrated hybrid system for clean and efficient power generation

Abstract

Thermo-economic and environmental analyses of a hybrid power generation system were performed in this study, which included a biomass steam gasifier, an indirect heated air turbine unit, carbon dioxide separation, capture, and sequestration using a molten carbonate fuel cell, downstream waste heat recovery via organic Rankine cycle, and steam Rankine cycle. Furthermore, multi-objective optimization was performed using response surface methodology to determine the operating state at which the system delivers the highest value of exergy efficiency while also having the lowest cost of electricity. It has been found that the conceptualized system delivers its optimum output when the air compressor operates at a pressure ratio of 9.41, the temperature at the inlet of the air turbine is 1100 °C, the molten carbonate fuel cell operates at 1500 A⋅m−2 current density with 80% fuel utilization, and the heat recovery steam generator pressure is 150 bar. The optimized values of the cost of electricity and exergy efficiency have been found to be 0.0993 $/kWh and 47.46%, respectively. At the optimum condition, the plant generates 1.3 MW power with an energy efficiency of 54.5%, capturing 5052.58 tonnes of CO2 in a year, producing $0.758 million in environmental benefit. It has been found from this study that the optimized hybrid power system yields better exergy efficiency and unit cost of electricity in comparison to the existing conventional biomass-based plants available in the literature.